Only one defensive player has ever won the Heisman, Charles Woodson. Woodson also returned punts and kicks, so I don't think a defensive guy has any shot. Another thing is that only juniors and seniors have won the Heisman, so Reggie Bush looks like a longshot. If Fitzgerald couldn't win as a soph, chances are Bush won't. I think that Orton kid is probably gonna win, and keep the tradition alive of Heisman QB's sucking it up in the NFL.
A good argument is always spoiled by someone who knows what they're talking about