
Why not try going back to the old OFAB rules from the compendiums, but modified slightly.
OFF FOR A BITE
At the start of every drive [Edid: Except the first drive of the game] roll a d6 for each vampire on your team with the OFAB trait. On a 4+ they can take to the pitch as normal, but on a 1-3 they decide to roam the crowd for food and miss the current drive. If one of your Vampires does fail the roll, you may instead place one of your thralls into the dead and injured box with a Bad Injury and allow the vampire to play as normal. The thrall has willingly given of himself to the vampire in order for the vampire to continue to play for that drive. No one would get spps for the casualties as they were self-inflicted.
The old rule was that the vampires would fail to show up for the start of each drive on a 1-3 and be able to play on a 4-6. This was detrimental to the team as the vampires ended up missing most of the game and you ended up playing with a thrall heavy team. In that case you may as well have played with Norse or Amazons. At least their players start with skills.
I would like to try something like this to take away the chance for vampires to injure their thralls permanently while still penalizing the team and making it less effective.
It would require a lot of judgement by the coach of the team as he would have to weigh whether or not to take a player permanently off the pitch for the game in order to allow a vampire to play for the current drive. You could run out of thralls quickly if you don't manage your team well and fail a lot of OFAB rolls, or you could be extremely lucky and never have to worry about it if your vampires make their rolls.
What do you think?
P.S. - I'm also not adverse to making the roll a 3+ to stay on the field and a 1-2 to fail the roll. I don't know if this would be enough of a detriment for OFAB.