I don't remember where I read this, years ago, but it was by someone who interviewed (with anonymity) a number of Heisman voters, both media and past winners. This writer noted that from his sample, the biggest factor for each individual voter was "how will I defend my choice."
His impression was that most voters seldom went with their gut, but instead voted for the least questionable (or, safest) resume. Just human nature.
Statistical leaders at QB (and in some eras, RB) frequently come from new or exotic offensive systems. Once a Heisman voter finds him/herself asking "How much of that resume was the player, and how much was the system?" that candidate becomes questionable, and it works against him with most Heisman voters.
My guess is that Hooker's injury (and his USCe performance prior to the injury) provided many voters the necessary cover to not engage the player-or-system question. But I wonder if time will eventually show that Hooker's ratio of interceptions-to-total passes thrown was under-recognized, and that he truly had a remarkable, historically significant season as a passing-running quarterback--in any system.
But he is not the first, in any aspect of life, to go under-appreciated. Nor is this is a world where "justice" has a history of running amok.
I'm bringing up this Heisman voting angle because, moving forward, Heupel's quarterbacks (if Heupel is still our coach, and if his offense has not been adopted by many more Power5 programs) are going to always have this question attached to their stats. So don't be surprised if 10 years from now we have at least two more Vols to add to the OP's list.