Would he be the worst Heisman Trophy winner of all time? I see a guy who hands the ball off a lot and makes his offense go, and doesn't make mistakes, but that's about it.
He would not even be close to the worst. Matt Leinart did the same things and had more talent on offense when he won.
McCarron hasn't thrown an interception since 11/12 of list year. Something like 300 attempts. Even for a game manager, that's pretty damn good.