What proof is there to accuse the Patriots of tampering?

There is no evidence yet... maybe not at all. If anything, this is all a matter of hearsay. No fanboy (Browns fan), just an outside observer.

Cheating is self-evident only when someone gets caught. You have no idea how many people might be cheating and never get detected. At any rate, the only evidence that the NFL has announced so far is that 11 of the 12 balls the Patriots supplied for their own use during the game were found to be underinflated when tested. The amount wasn't much, around 1 PSI for most of the balls. There's no explanation yet of how it happened, whether it was accidental, or someone deliberately tampered with the balls, or if just a matter of simply physics, the balls being colder then they where measured on the field then when they were measured in the Pats locker room.

None, except for the fact that 12/13 footballs that were New England's balls were under inflated while all 13 Colts balls were within specs. No one knows who or what happened yet. Obviously someone tampered with the pats balls. It will come out; whether we all believe it is another question.

The measurements of the footballs is already a lot of evidence. You must be another Patriots fanboy apologist.