I think we can apply the Occam's Razor to this ball situation.
What do we know? We know the balls where under-inflated by NFL standards.
We know the balls where properly inflated prior to kickoff.
If the balls initial pressure was regulation and the post measurement showed deflation then the most likely answer is someone or something took the air out.
"If you eliminate the impossible, then whatever remains no matter how improbable, must be the truth." Sherlock Holmes.
So either the laws of physics didit or the Pats didit.
The answer with the fewer assumptions is that the air was let out by someone. (Just my opinion)
However I do not feel the punishment fits the crime since there is no smoking gun.
"You were not there for the beginning. You will not be there for the end. Your knowledge of what is going on can only be superficial and relative" William S. Burroughs