There's a PSI regulated range, so yeah, a rule was broken, or just a regulation, if there's a difference. My guess is there is a difference, or at least in how much the NFL cared until this whole thing went down. For instance, they seem really intent on monitoring player uniforms and will fine people for the dumbest shit, but the PSI of a football they just sorta leave to a gentleman's agreement and gamesmanship to handle it and only give a token check of the footballs and don't really maintain much control over them. How easy would it be to have the QB approve the ball, then the refs or a league official keeps control of them the next few hours until game time?
I'M NOT SAYING IT WAS A STING OR CONSPIRACY!!! Just dumb the league is blowing up this story to investigation levels when all they had to do was not be dumb fucks and actually make a minor change to how balls are handled if they really cared that much.
The impact is probably not nearly as much as people make like it is, but I'm sure there is some. I've not heard a single QB current or retired really say it makes a huge difference unless the ball is way out of specs, which is partly why the new rule/reg was put into place, because QBs would get to an away field and the ball would be solid as a rock. In games/quarters we know for absolute certain the balls were monitored and within regulation he played pretty well. Early on there were hilarious skits on ESPN where they took pros and tried to see if they could tell the difference to varying success. Maybe they fumbled less, though I attribute that more to the Pats really, really hating fumbles enough they seem to actually work on it and bench dudes who fumble. It's a culture, thing, and maybe it helps, but while they may have deflated balls to help Brady, they sure as shit didn't do it to help their running game, so if that happened it was just a nice side effect.
The funny thing is Peyton Manning lobbied with Brady to let visiting teams provide their own footballs, and I think somewhere has gone on the record saying he likes them soft, and one of the things some QBs have talked about is under-inflated balls make it harder to throw a spiral, which is maybe why Manning looks like he's tossing decoys for duck hunting half the time?
This is all dumb. All of it. It would be like a team complaining an opposing pitcher is cheating, MLB investigating, and suddenly saying they had no clue pitchers were doctoring balls and using various substances, and that the bits of pine tar and spit were all providing them an advantage, and then opposing fans talking about that pitcher being a cheater and that he should be banned for life.
It's still all Brady and the Patriot's fault though, of course, from the beginning he should have just said that it's no secret he likes his balls on the lower end of the spectrum and the Pats were going to investigate to make sure nobody took that known fact and tried to do something they shouldn't have and that he's sorry if anyone inadvertently did anything on his behalf without his expressed wishes, yadda yadda. And insist they start checking Brady's balls every quarter, knowing the Pats were still going to kill the Colts and anyone else.
Instead, the pretty boy and the team that is like Pop and the Spurs who flex their competitive middle finger at their respective leagues anytime they're challenged, basically said fuck you to the NFL, and now the NFL is doing whatever they can to save face and prove you can't go against the Shield.
And meanwhile, you now have seething retards on both sides of the fence claiming it was either a sting/conspiracy or claiming it was a coverup, when in reality it was just a lot of posturing and dick wagging and somewhere in the middle of the fuck-you-retards is what's actually going on: not much.