It seems like QBs that win the Heisman tend to be a bust, whereas the RBs that win end up pretty successful in the NFL.
Since 1980 the only remotely successful QB has been Carson Palmer, and his success is very recent. Guys like Flutie and Testaverde have had long careers, but I'm not sure they're future hall of famers.
The RBs on the other hand do pretty well - Marcus Allen, Herschel Walker, Bo Jackson, Barry Sanders, Eddie George, Ricky Williams and Ron Dayne. Not all are equal, but I'd say they've all done pretty well.
Maybe the Heisman is the kiss of death for a QB, but a decent predictor of success for a RB?
Source:
Heisman Trophy Winners