Just read an article posted on Yahoo that there were two baseballs used last season and there is really no way to know if the usage was equal amongst all teams. I hadn't seen anything post here yet.
Could this mean that the Yankees were served a steady dosage of the deader balls while other teams got the heavier / livelier balls?
One will never know. But this is another case of MLB shooting itself in the foot, while trying to claim the player's union knew what was going on.