The WFTDA rule is that penalties are enforced based on a player's position when she commits the foul.
If a jammer commits a major foul, she has to sit immediately and her team rolls without a jammer for 1:00. That's pretty obvious.
If a player commits four minor fouls, she has to sit the first 1:00 of the next jam, and her team rolls without a player in the position (jammer/pivot/blocker) which that player was skating when she committed her fourth foul. That's less obvious, and arguably unfair in certain circumstances, but that's the WFTDA rule.
In the first period June 2nd, quite a few jams began without a Queens jammer. This was because their jammer picked up her fourth minor during the previous jam. Not all four of her minors were necessarily picked up while she was jamming, just the fourth one.
What isn't so obvious to see 'from the outside' is that if a team has a girl who usually skates as a jammer picking up three minors, they might send her in as a blocker with the specific mission of picking up her fourth foul as a blocker. That way she can clear her slate and get back in as a jammer two jams later with a low foul tally. This puts a significant (but interesting) burden on team management to manage their girls' foul situations during a bout.
Personally i find it to be a bit silly that the rules upshot sometimes encourages a jammer to foul to get her fourth as a blocker, but that is the rule nonetheless and it's what we enforce. And it's better than a number of other less appealing alternatives.
We're still struggling to devise a system which would allow the crowd to see the running foul totals for each skater, so as to de-mystify the whole process. Some other leagues are in venues where they have nice flat wall space against which they can project custom-coded flash programming to supply this information. At present GGRD does not have this luxury.
Specifically in the first period of the June 2 bout, the Queens jammers weren't doing anything outrageously egregious, just a high volume of the typical minor-foul things jammers do, like blocking into a girls' back, intentionally cutting the track, or swimming with forearms. Brooklyn jammers were doing these things as well, but didn't as frequently encounter the misfortune of picking up a fourth foul while doing it.