We're assuming it was done after the refs approved the game balls.

We're assuming that the refs even really check the game balls before approving.

We're assuming that the Patriots are the only team doing this.

It's all pretty stupid. My guess is that every team does this to some extent, but everyone hates the Patriots so they get snitched on when other teams wouldn't. The Patriots are shady, no doubt but the other teams are whiny bitches.