The PSI differences may be miniscule to a layman, but according to comments some ex-pro quarterbacks have been making, two less PSI makes a difference in performance.
Given the stuff I’m seeing it seems to be more about personal preference than performance. Rodgers likes his over 13.5 and it certainly doesn’t look like that hinders his performance. Eli apparently likes large highly raised laces. Brad Johnson is willing to pay somebody $7500 to get them scuffed up. Haven’t seen what Peyton likes but he was willing to lobby the competition committee to make it legal to tweak them and made a good enough case for them to allow it within certain parameters. And this hasn’t even gotten into all the stuff kickers used to do to balls that caused the league to bring in the factory fresh K balls into existence. The more I think about the more I’m thinking Rodgers is right, either delete the rule or loosen up the regs to just outlaw ridiculous changes.