I think one thing that's playing against Rex right now is he didn't have a lot of that early season hype surrounding him like many of these other Heisman contenders did. Yes, one could argue that Suh didn't get a lot of attention until after the championship game, but people already had him throw in there before that game. It just wasn't until after the game that he really skyrocketed.
Furthermore, Nebraska won't be playing for a national title this year, and they'll have to at least play for and win the Big 10 title in order for him to seriously have a chance to win. He'll also need to get around 1,600 yards on the season. This is the biggest issue for Rex. Even if we make it to the title game, he needs to keep that production up and we need to playing for at least a BCS bowl. It's been awhile since a player not playing in the MNC or a BCS bowl won the Heisman. Almost every one of those Heisman frontrunners has a big game coming up they could potentially lose. If we don't lose another game, those teams do, Burkhead keeps his production up, and we win the Big 10 title, it's possible Burkhead could be in New York.
But that's a lot of ifs.