So this has been a big discussion in national sports news of late and I figured (and because I'm bored) I could offer a little insight as a former equipment manager on the subject. #1 All footballs are inspected by the officials prior to the game and I'm sure they all passed the approval, no sort of NFL conspiracy here. #2 After the officials look at the footballs, they are placed back in the game ball bag where realistically anyone has access to them, but mainly it is just the equipment staffs and the ball boys. Now usually it is relatively easy for officials to monitor the game balls, but on a game such as this where they probably are doing more important game prep or warm ups, and there are a plethora of people on the sidelines, it is very easy to access the ball bag and do any type of tampering with the balls. The subtlety of the tampering would go unnoticed likely by almost everyone unless you either A) you have a sensitive feeling for this sort of thing or are someone who has enough experience with footballs of various pressures that they can tell, or B) you again test the ball. #3 The majority of the effect would be solely personal preference, most kickers like the ball pumped all of the way up, receivers usually prefer a little less air in the ball, and QB's are sort of a mixed bag, some like it super pumped, others like it a little less. Some QB's like it more broken in, some like them brand new. It's a personal preference and has a negligible effect on the game. (NOTE: If the official is unable to notice a difference in the feel of the ball over the usual course of the game until it is brought to their attention which appears to be the case in this game, the ball likely never fell below 11PSI which to the average person would feel the same as a ball between 12.5-13.5 PSI.) #4 So despite my complete dislike for the New England Patriots, I have to say that any effect that this would have had on the game would be negligible at best. USC got in trouble for this not that long ago, and there it was much the same thing that the QB just preferred a ball that was a little softer and that is my guess as to what happened here. So I hope that offers some insight into the event from someone who has been on the inside and seen this happen first hand and has a decent amount of experience with footballs at a high level.