Wednesday, October 31, 2012

The Fan Experience

Everyone who plays derby has their own reasons, from an excuse to stay fit to loving competition.  For many, this includes a chance to compete in front of an adoring public, aka the fans.  I honestly don't know of a single skater who prefers closed bouts to open ones, as they love the sound of that crowd!

Thing is, often that crowd is the last to be considered when setting up a bout.  1st comes the track, then the skaters' needs, then those of the refs and NSOs.  Then a bunch of chairs are set up where there's space for the crowd.

This is fine if you're just interested in showing some people how roller derby works.  If, however, you want that crowd to return bout-after-bout, you have to put a whole lot more effort into improving the fan experience.  Here are some simple ways of doing just that:

The Demo Jam/Kit Checks

Some teams have let the demo jam fall by the wayside because they assume that a high enough percentage of their audience knows how derby works that they don't need to explain it any more.  They leave that to the announcers and fellow audience members.

As well, some teams plan kit checks to work around skate-outs really well.  Visitors skate whilst home are checked, and vice versa.  Otherwise, the fans get all excited during skate-outs, then have to hold on to the excitement for what can seem like a long while.  I have personally seen it really hamper a good atmosphere.

Combine the two?  Almost every bout I've been to uses a projector for the scoreboard.  This means that teams can show videos!  Why not show a demo jam/explanation of the game on the scoreboard during the kit check, then do skate outs?  A good video will have the crowd excited a bit, then the skate outs will send them over the top, and they'll be psyched for the first jam!

Premium Seats

LRG do this, and you should, too.  Separate seats, that are more comfortable, and have waiter/waitress service.  They cost a bit more, but come with amenities.  One team in Carolina has a set up where there's two couches, each with a cooler full of beer and a subway party platter.  One is for hire, the other a door prize given out to one lucky fan via golden ticket in the programme.  Who, then, wouldn't want to be the sofa king?

Some fans are willing to spend extra money on sports, and want that added comfort.  It's not only a good source of income, but it shows fans that you're willing to go the extra mile for those superfans who want to make a special event out of roller derby.

Halftime Show/Official Timeout Distractions

I know British sports don't do them, but something to watch during that 20 minutes of dead time is a great idea.  I've seen professional roller disco skaters come out for halftimes, games involving audience members, and even a 10 minute junior derby bout!

Sure, some of the fans will be going to the loo or to the beer line, but boredom is poison to a sports audience.  There has to be something going on in the middle to keep them entertained, maybe 2 skaters demonstrating their jumping ability or a derby duel or two.  Even doing the raffle would work.  Just make sure to keep the excitement up!

Same thing goes for the official timeout.  These are getting fewer and shorter, as the minor passes into oblivion, officials hone their craft, and head refs better ignore requests for official timeouts from bench managers and captains who have already burned an official review.  However, whilst they're still in existence, there has to be something to distract the audience.

Jammer dancing does this well, but only works for short timeouts.  So, announcers and organisers, get something going to distract the audience.  Could be as simple as having a league member who's not otherwise involved leading the wave or some other cheer.  Or, why not have a dance-off in the audience to some song?  Make sure the audience don't really care that the action's on hold for a minute.


What is it with derby bouts and daggum cake?  Every bout there's at least one cake, if not multiple.  I am fed up with cake!  Please, let's have the treat after a bout be savoury for once!  Wings, fried scampi, even pizza.

I was coaching against Croydon Roller Derby, and they had the best damn food spread at the after party I've seen in the whole of the UK.  They had chips, spring rolls, onion bhajis, samosas, wings, and all number of other treats to eat.  Of all the after parties I've been to, they won.  No damn cake, but real savoury food!  I know this one's personal, but learn from them!

When next you plan a bout, please put due care and consideration into the fan experience.  Do that a few times, and you'll see your attendance climb.  You may even have regular fans who have no connection to derby other than "I showed up once, it was awesome, now I go regularly."  That reasoning is exactly why I got involved in derby in the first place.  Roll on!

Monday, October 29, 2012

Rule change still coming?

I'll open with the sarcasm: it's still on its way?  This is kinda like the little time on the satnav ticking down, but at a much slower rate than the usual clock.  "Go on, you're only 5 minutes away!" it says.  Funny thing, I was 10 minutes away 2 hours ago.

I love that they're stringing us all along with these announcements every few months.  It's like working a job on commission with the whole "oh, it'll pick up soon, I promise" from the boss.

Alright, sarcasm aside.

I'm excited!!!  I truly am excited by this announcement.

I know that the WFTDA are giving us a bit more info every announcement, to keep people enticed and following them closely, but this info is great:

Single whistle starts

Read that line again, if you'd like.  The jammers and the blockers will all be released simultaneously.  What will this help with?  Well, quite a few things.

First, the slow start.  Remember gaming the system so that your blocker who's standing in the box will be released before the jammers are?  That bored the tears out of the audience, and your competitors, and likely your teammates.  Sure, they did it because they though it would help, but they probably didn't like standing there slowing the game down.

Slow starts mean less derby will involve skaters in motion.  And what's the point of derby without skating?

Second, the scrum start.  One team has to take a knee, leaving them at a disadvantage.  Single whistle fixes that.  Most jams now start with the jammers being released less than ½ second after the blockers.  Single whistle makes that standard.

Now I don't know if they'll institute the "blocker box" a la USARS and MADE, but they don't necessarily need to.  If a team doesn't want a traditional scrum, just have their jammers back up about 5 feet.  Also, a blocker box doesn't necessarily kill the mad-dash-for-the-jammer-line which risks injury.

So, this is a large step forward.  Single whistle AND no minors, and derby will be much smoother running and easier to officiate, learn, and play.  Sure, tactics will have to change, but that's not necessarily a bad thing.  In fact, that's an opportunity for some new teams to be the ones that come up with the clever play to take the derby world by storm.

Who knows what else may be hidden in those rules.  All I can say is, I'm a bit more excited.  Roll on!

Sunday, October 28, 2012

Women's UK & Ireland derby chart 28-Oct

The rankings presented here are in accordance with the rules and consider Rollin News as the authoritative source for bout scores concerning UK & Ireland teams.  If a score is not listed as open or public on that source, it will not be included in this ranking.

Disclaimer aside, here you go.

Thursday, October 25, 2012

Sportsmanship & derby

Seriously, for a sport with a strong DIY ethos, there are some surprising gaps in sportsmanship expectations in derby.  I enjoy watching a skater be a "hot dog" on the track; I'm not really talking about being a showoff here.  I'm talking about some deeper issues.

The High Five

This is one of my favourite derby traditions: the fans all line the track, and both teams each take a lap, slapping fives with the audience.  It's one of those wonderful things about derby that blur the participant/audience division line.

Thing is, both teams need to be given fives.  I have seen audiences only offer a hand to the home team, or to the team they travelled to support.  Sure, there might've been some bad blood in the bout, but it's over now.  If you're going to step up to the line for one team, be the bigger derby supporter and step up for both teams.  Both teams competed, both worked hard, thus both deserve support after the bout.

The Score

A win is a win, right?  Why do we need more 237-45 scorelines?  They're not fun to watch, they're not often considered fun to play in, and they're a massively missed opportunity.  There's nothing to be gained by confirming the win with a score ratio like 4:1 or worse.

If the win's in the bag, it's time to experiment.  New formations, new plays, even new positions are worth trying.  Take a blocker, and give her a go at jamming.  See what happens when you play 2-offence.  Run power jams the old way.  So much of derby is done with the scrum start now.  Why not switch up once the win's already settled?  You may need to when you're behind later, this is a good time to practice.

You've already proven your system works better than theirs.  No need to keep rubbing it in.

Preferred Leagues

This one really gets my goat.  Picture this: mixed scrimmage, head ref in that role for the first time ever. Captain of the blue team is part of a top-10 league.  Captain of the red team is part of a team ranked in the mid 40's.  Upon being introduced and hearing this, the head ref directs the entire pre-bout chat to the member of the higher ranked league.

Or picture this: boot camp, a skater comes over to chat to three others who were not in their team's tops.  Two were from a league in the 40's, one was from a league in the top 15.  Once she learned this, she basically stopped talking to the two from lower ranked leagues.

Do I even need to say why this is unacceptable?  A skater becomes less worth talking to, less worthy of respect because of who she practices with?  Wow.  Just, wow.


That's my term for those who are involved in derby, but don't skate.  They seem to be the most marginalised in derby.  This includes the NSOs, of course, who are frequently mentioned and thanked, and shown respect by the skaters.  It also includes announcers, DJs, seating ushers, ticket takers, programme handers-out, cameramen and -women, merch-stand operators, and derby journalists.

This group is not shown much respect by the skaters.  The "for the skaters by the skaters" ethos is expanded in the mind of some to mean that the flatfoots are working for them.  When flatfoots offer an opinion on derby, it's discounted with "oh, but you're not a skater."

The derby community is far more than skaters.  That's why I usually call it that!  Years ago, the only people who would be called "derby people" were skaters.  Now, with the growth of the above positions, there are loads of derby people who don't skate.

Derby wouldn't be derby without them, and they're a part of the community too.  Thus, they deserve respect as well.

Victory Songs

Congrats, you just beat a team who travelled to your place to play their first ever open bout.  "We are the champions"?  "Na Na, Hey Hey, Goodbye"?  The "Hey, you suck" song?  Really?  That just seems a bit cocky.

Nothing against your taste in music, but the timing's off.  That sort of thing goes against the culture of the high five, the hugs & handshakes, and the group photo after the bout.  Keep it in check, please.


This one's been done to death, but I'll say it too: respect the refs!  That doesn't mean you have to call them "sir" or "ma'am" but it does mean that you have to accept a decision with dignity.

I'd like to see an end to the "tradition" of jammers signalling their tally of points to the ref after a jam.  This is called demonstrating in baseball, and is one of the most common reasons for an ejection.  The referee said 2 points, you can either go in and challenge it officially or accept it.  Attempting to undermine the referee's authority by signalling 3 shouldn't be an option.

As well, when chatting to the derby public in general, do not blame the refereeing for a loss.  This includes the statement "well, the refereeing was a bit spotty" and "I'm not sure some of the calls were exactly correct."  Those are just attempts to make "we would've done better if the refereeing had been the way I wanted it to be" sound better.

A great coach once told me "if you blame the refs, it means you don't want to learn to win."  The referees aren't crooked.  They're just not, so stop.  They're working hard to keep the game you play within the rules.  Show them respect.

I think I've covered enough here.  Derby's a young sport, these are growing pains.  But we should show more respect for everyone in the derby community.  After all, it's all of us together who make derby such a great thing.  Roll on!

Monday, October 22, 2012

The Derby Duel

This last weekend, two of the most exciting jammers in Europe challenged each other to what I can only call a Derby Duel.

2 Minutes

2 Jammers

1 Winner

Skate around the track.  Whoever is further ahead when the time expires wins the duel.  All normal derby contact allowed.

Do you skate fast?  Do you go for hits?  That's all up to you and the one-on-one strategy you choose to employ.

It's really the ultimate test of jammer-on-jammer ability, and a great way of finding out who has the skills to be a good jammer.  No pack to get in the way, or offer assistance.  Just pure one-on-one.  Also, it's the most excitement you'll ever see on 16 wheels!

I can see this being a good training routine--if a team wants to work on jammer skills, what a great way to drill cleverness and contact all in one go.

There is a precedent for this sort of thing.  Baseball has the home run derby and basketball has a slam dunk contest.  Both are displays of a basic skill taken to the extreme, and given a high degree of showmanship.  Both are a part of the all-star festivities in each sport.

I would like to see Derby Duels taking the same sort of position.  If there's a tournament, have a duel at the halftime of every bout.  Thus, there will be a duel tournament nested within the main one, giving the audience no excuse to leave the track!

Or simply arrange a few to take place at the half time of a regular bout.  I'm sure there would be loads of skaters vying for those 4 spots in a duels playoff.  They wouldn't even need to be from the leagues involved in the main bout.  It would only take 6 minutes to get a champion, and keep the crowd in their seats and screaming for the first part of halftime.  Way better than any other halftime show, by far!

The first derby duel was started as a display of sportsmanship and fun, plain and simple.  Two jammers only had one opportunity to face each other all day, and wanted another round of it.  All that was said was "I jam against you, and you speak it."  That 2 minute game showed 100% fun.  It was nothing but the sheer joy of derby, and the crowd were right up against the outside line screaming.

Sunday, October 21, 2012

Women's UK & Ireland derby chart 21-Oct

The rankings presented here are in accordance with the rules and consider Rollin News as the authoritative source for bout scores concerning UK & Ireland teams.  If a score is not listed as open or public on that source, it will not be included in this ranking.

Disclaimer aside, here you go.

UK & France men's chart, 20-Oct

The rankings presented here are in accordance with the rules and consider Rollin News as the authoritative source for bout scores concerning UK & Ireland teams.  If a score is not listed as open or public on that source, it will not be included in this ranking.

Disclaimer aside, here you go.

Wednesday, October 17, 2012

WFTDA's new playoff structure

Let me open by saying like like like like like.  I really like the idea of 4 1st round playoff tournaments, rather than regions.  Some of the regions are weaker than others, and it makes sense to take the top 40 worldwide, rather than the top 10 from some geographical and uneven regions.

What did they mean by S-Curve seeding?

Well, simple seeding's easy to conceive of, but a 40 team tournament makes things complex.  The theory is that the total rank of each "branch" of the tournament be equal, and to do this one fills in the chart below in an S-curve type manner.  Each team is represented by its rank, which becomes its "seed."  Follow the counting numbers in order, and you'll see.

1 2 3 4
8 7 6 5
9 10 11 12
16 15 14 13
17 18 19 20
24 23 22 21
25 26 27 28
32 31 30 29
33 34 35 36
40 39 38 37
205 205 205 205

So this way, each of the four 1st round tornaments have a total seeding strength of 205.  Thus, the four tournaments have been seeded equally and there is no bonus to being in any one in terms of ease of reaching the final.

So it's more fair in theory, but what are the risks?

--First off, rankings are a bit questionable.  Glasgow have a 40% chance of beating LRG, and Montreal are one of several teams in the East Regional who were not as highly favoured.

European teams are undervalued, as teams vote for rankings.  With the exception of LRG, only Euro teams watch other Euro teams play, and thus they are less likely to be highly voted by North American voters.

This effect is not so great when considering only one region at a time.  Voters outside the East region need not concern themselves with Europe.  However, when all leagues are grouped together in one ranking, this effect will manifest itself much more strongly.  

This, to me, suggests either the computer poll or the DNN power rankings.  The first, like the one I run, has no problem ranking large numbers of teams who play unbalanced schedules.  The second is totally done by human intuition, but by the intuition of "professional pickers," those who are focussed solely on determining which teams are ranked where.  These pickers see every result publicly listed, which are the only ones that should ever count, and thus should have no bias towards one continent or another.  Either one eliminates the bias of having open voting.

--Second off, there is a likelihood bordering on a guarantee that some teams will have to travel much further to their 1st round tournament.  Right now, a similar structure is used by the NCAA basketball tournament in the USA, where the top ranked teams are assigned to the location nearest them, and teams seeded further down must play where their rankings assign them.

This system would work in derby, but so would an adjustment to what's been discussed above.  If a human poll were used to determine the rankings, everyone would acknowledge that there is some uncertainty between who's picked at 8 versus 9, etc.  Thus, a selection committee could "fudge" the seeding a little bit to ensure that LRG don't play in California, for example, or Rat City in London.

Another answer would be to choose the four locations spread throughout the USA.  Let's say the tournaments are in four cities: Charlotte, NC; Little Rock, AR; Indianapolis, IN; and Portland, OR.  The four tournaments are then seeded according to A, B, C, and D in the chart above.  After the four tournaments are seeded, they're connected with the four locations, using an algorithm to minimise total mileage travelled.  Thus, LRG would likely play in Charlotte, unless they were in the same tournament with Victoria.

And those that weren't selected?

This is one of my favourite parts of the announcement!  Instead of simply calling their season over, they'll be introducing a Division II tournament so there'll be more silverware.  I'm not the only person who's been suggesting that the WFTDA institute tiered structure like the football league, and now that seems like a more distinct possibility.  I'd like to see it expand to 40 if successful, but it's a great move for the WFTDA.

Final verdict?

Very yes.  There are still questions which require answering, but this (and the impending rule change) is an opportunity for the WFTDA to make a massive step forward towards making the whole system run more smoothly, evenly, and fairly.  I hope, hope, hope that they take the bull by the horns here and help organised derby live up to its expectations.

Read more?

Monday, October 15, 2012

Women's UK & Ireland derby chart 14-Oct

The rankings presented here are in accordance with the rules and consider Rollin News as the authoritative source for bout scores concerning UK & Ireland teams.  If a score is not listed as open or public on that source, it will not be included in this ranking.

Disclaimer aside, here you go.

Saturday, October 13, 2012

UK & France Men's Chart, 13-Oct

The rankings presented here are in accordance with the rules and consider Rollin News as the authoritative source for bout scores concerning UK & Ireland teams.  If a score is not listed as open or public on that source, it will not be included in this ranking.

Disclaimer aside, here you go.

Friday, October 12, 2012

Demo Jam Script

Alright, y'all, here's a sample script for how to run a demo jam at a bout.  If you're doing a bout with a large number of derby virgins, it may be a good idea to continue this old derby tradition.  This one is tailored to a UK audience.

I like to do it with a wireless mic standing on the track pointing to the various skaters.

Here we go:

Roller Derby is played by 2 teams of 5 skaters each skating in shifts called Jams.  These players are divided into three positions.  At the front, we have the Pivots and the Blockers.  All together, they form the Pack.  

At the back are the Jammers.  These are the ones that will be scoring points, and the ones to keep their eyes on.  They're easy to spot with the star on their helmets.

One whistle [tweet] releases the pack, and two [tweet tweet] release the jammers.

The jammers try to make their way through the pack, helped by their own blockers and hindered by the other blockers.

The first jammer out of the pack obtains lead jam status.  More on that later.  The blockers are not allowed to back block, or use elbows to stop the jammers, and the jammers cannot cut the track around the blockers.

On the second pass, the jammers score points for every opposing blocker or pivot she passes.  These are signalled by the jammer ref in the middle.

When she's had enough, the lead jammer can call off the jam by placing her hands on her hips like this.  [tweet tweet tweet tweet]

The four whistles end the jam, each team is allowed to substitute as they see fit, and 30 seconds later we start again.  Simple enough?  Enjoy!

Thursday, October 11, 2012

Lost Tactics

There are a few things that have, sadly, disappeared from the game of roller derby.  Without a doubt, the sport is improving as skaters get better by leaps and bounds, coaches discover new strategies, and referees hone their craft harder all the time.

However, I've been watching derby for 5 years now, and there are things I loved to see in the game when I first started that have sadly gone by the wayside.

The Assist

Jammers run out of "juice" during a bout.  Why not help 'em?

By assist here, I specifically mean the whip.  Inside whips, outside whips, hip whips, even the egg-beater.  Ever want to drive a crowd into conniptions?  Use an egg-beater.

Simply, where have whips gone?  Well, all the various leagues I've worked with have been focussed on "defence first" for their blockers.  When there's offensive assistance, it's usually one blocker acting as a screen for the jammer.  This is helpful, no doubt, but it usually works best on the initial pass.  Most jams' initial passes have one team with a 4-wall at the front and the other with a 4-wall at the back, thus a single screen can get a jammer past 2 or 3 blockers.

However, when the play breaks down on the initial pass or frequently on a scoring pass, there's often one friendly blocker and one opposing blocker near the front of the pack.
In this situation, the pink blocker might normally simply block the green pivot to the outside.  Should this block flatten the pivot, then the jammer's home free.  However, should the pink blocker merely surge or screen the pivot to the outside, they may become free to chase the jammer out toward the front.

This is whip time.  Without assistance, the jammer is limited to her own acceleration, which is similar to the pivot.  However, with a whip, that jammer can get much, much higher acceleration and have the pivot beat before she can even start to chase.

I have seen this scenario time and time again in bouts, but the blocker doesn't offer a whip, and the jammer doesn't often take it if offered.  What happens next is the pivot comes forward around the screen and takes the jammer out.  Then she's recycled, etc., etc.

When a jammer comes along, you must whip it.  Whip it good.

The Star Pass

I love the star pass.  It's one of the few opportunities to really take and scramble the plans of an opposing team.  If you watch USARS or MADE derby, which allow the pivot to go and score without passing the star, you'll see that an attacking pivot drives the overall strategy in those rulesets.  However, when I start to talk to teams about the star pass, I always hear the same thing: "But you can't get lead jam status!"

Right, that's true, the star pass isn't right for situations when you consider lead jam status as your #1 priority.  What about those situations where you don't?

  1. Opponents have lead jam
    • Jammer is trapped behind a sturdy wall
  2. In front on a scrum start
  3. On a power jam, with a really knackered jammer
In the first and the third, lead jam is unimportant.  In the first, lead jam's already been conceded.  In the third, the decision's been made to play the power jam to the end, rather than to call it off.  Let's go through them point-by-point.

  1. Lead jam's already been lost.  There's no point in preserving lead jam status, and the jammer's trapped behind a solid wall.  Why not air-lift the jammer out of trouble?  No need to practise the peg assist, just have the pivot slide in front of the wall, then pass the star right over that wall.  Now the pivot-cum-jammer is free to chase the opposing jammer around.

  2. Well, you see the scrum start coming, and your team's stuck at the front.  You've already lost lead jam in this scenario a few times, and so you want to ruin your opponent's positional advantage.  Why not have the pivot line up on the extreme outside, and the jammer right behind her.

    When the jammer whistle goes, the panty can go right over the back wall, and the pivot-cum-jammer is out the front of the pack.  The now ex-jammer is free to help block the opposing jammer.  If the team running the star pass does a great job, the new jammer will have time to come around and score.  If not the jam will be called off, and the team that assumed it had the advantage will be frustrated.  Do this a few times, and they'll be forced to change their tactics.  Congrats, their strategy is fouled.

    Want to be even more clever? There are ways to foul their strategy even more, some involving not even conceding lead jam status.  This I call the option.  The jammer has the option to fake a pass to the pivot and keep the panty, or to pass it off.  As long as the pivot hasn't put it on yet, she can even pass back to the jammer should she get into trouble.

  3. On a power jam, you may want to utilise every second available for scoring, and not call the jam early and "waste" power jam time securing lead jam status for the next jam.  In that case, if the jammer's knackered, it may make sense to simply hand over the panty to the pivot.  Just make sure this is done in the engagement zone but that the panty is on before any opponents are passed.  Otherwise potential points may be missed out on.
If you'd like to read more about the star pass, check out the Team Sealand star pass manual.  This explains the option in even more detail.

I would love to see more teams use these too tactics in bouts.  They would make the sport more exciting to watch, as well as throwing off teams that are too constant in their strategy.  Let's see some clever derby!  Roll on!

Monday, October 8, 2012

Women's UK & Ireland derby chart, 7-Oct

The rankings presented here are in accordance with the rules and consider Rollin News as the authoritative source for bout scores concerning UK & Ireland teams.  If a score is not listed as open or public on that source, it will not be included in this ranking.

Disclaimer aside, here you go.

Wednesday, October 3, 2012

The science of the lineup

Anyone who has acted as Lineup Manager, Bench Manager, or Bench Coach knows that who you send in can be a big issue.  Things get very hectic very quickly, and 30 seconds can seem like not enough time to get things sorted.

However, there is another sport that has substitutions just as free as roller derby, and a similar time limit.  I'm talking, of course, of American Football.  In the NFL and college, teams have 40 seconds between plays, and in high school it's 25 seconds.  That means 25 seconds to shift who your 11 players are, and get ready for the start of the play.  Sound hectic?

It's not!  Most football teams have a core group who, bar injury, are on every single play.  Thus, substitutions are just to fine tune running backs, wide receivers, etc.

So, how can we make it so that derby lineups work as smoothly as football ones?  There are a few options:

The Classic
This is where you write out a chart, jam-by-jam, and send that group in each time.  You set the lineup for jam 3, as written on the chart, on the next-jam bench as soon as jam 2 gets underway.  Problem is, by the 5th or 6th jam, penalties will likely start to foul the chart.

This is why the lineup manager is usually stressed right here.  Drew up a nice plan, plan didn't work.  Oh, hello stress, where ya been?

As this system leads to guaranteed stress, unless your team commits 0 penalties, it is flawed.

Alphabet System
This is where you rate your skaters with A, B, C, and D.  The goal is to have D skaters on as rarely as possible, and as high a value as possible every jam.  Thus, if there are 2 As, 2 Bs, 1 C, 2 Ds and 2 Jammers on the bench, the next lineup would just be the As and Bs.

This system is really low stress, as it's remarkably easy to determine the next lineup.  There are a few major limitations, though, including endurance and flexibility.

The skaters ranked as As will skate every other jam.  This means that they will be worked much harder than the Cs and Ds.  They will undoubtedly experience fatigue, and eventually this will reduce their ability to the point of those Cs and Ds who have been waiting on the bench.  And, if endurance isn't an issue in a given bout, that means you're not skating hard enough.  If you're not being pushed to the limit, then you're not playing difficult enough bouts.

What about jammers who are also good at blocking?  I mean the true double threats.  They're likely ranked as As for blocking, which means that if the system is applied rigorously then they won't have enough time to recover after jamming.  To use this system with double threats takes a high degree of planning ahead.  It's a potential source of stress.

Hockey System
Ice hockey also has free substitution, and they do it by "lines."  A line is a full rotation, similar to a lineup in derby, who practice and work together.  I attempted to use it in derby, to some success, but it will take some more development before it's done.  Here's the setup:

Mary MJSharonJB

So, each line has 2 jammers, and 6 total skaters.  Thus, each skater stays with her line.  If a skater goes to the box, she'll join the opposite line for the remainder of the jam when she exits.  Then she'll sit on the bench to rest or stay on the track so that she'll return to skating with her line.

The unassigned skaters are available to take over in cases of injury, or fatigue, or if a bit more reshuffling is necessary due to penalties, etc. to keep the lines together.  Otherwise, this makes the lineup manager's job much easier.  Instead of 9 skaters to choose from, there are only 6.  "Salt's on the track?  Alright who from Pepa's sitting the next one out?"

Other Options
If you're a team that uses the star pass frequently, or plays USARS/MADE derby, it might make sense to have jammer-pivot pairings as unbreakable combinations.  The rest of the lineup is filled in around them.  This is similar to the NFL system of having a core group and making the adjustments around them.

Or, you could put blockers in pairs, and build the rest of the lineup around those pairings.  Any coach knows some skaters work better together with specific other skaters.  This might be a good anchor for a lineup.

Both of those can be incorporated into the systems above, or could be a system of their own.

Be clever!  If you like what I've written, but only like 70%, then riff on it!  Figure out what works for YOU, not what works for some big team that do well in WFTDA.  They're not you.  Roll on!