People don't even remember Keith McCants he was such a bust. Desmond Howard won the super bowl MVP or else he would be up there. I'd say Mandrich because of the 3 guys drafted right after him (B. Sanders, D. Sanders & Derrick Thomas)
The Heisman doesn't and isn't supposed to predict who the next big pro football player will be. It factors a players contribution and success in the NCAA and to his team. At the time.... yes, even Eric Crouch filled those requirements.
Take new Heisman winner, Jason "I didnt even get drafted in this years draft" White... of course it means nothing to the NFL.
No doubt...look at the "great" Oklahoma QB Jason White. He did just about everything a college QB can do...yet he will have no NFL career to speak of. I am not clowning on him, just saying the Heismen does not speak much for future successes.