Performance based contracts just won't fly in professional sports (unless it's an aging vet or someone trying to comeback from a horrific injury or suspension). So what teams should do is start fining the cr@p out of the players for every false start, every dropped pass, every missed assignment, etc. And so the owners don't look cheap in the process, they can have all the money go to charity. Players would perform at a higher level and it would be a good PR move.
It won't work, but I think it's a good idea nonetheless.