2001 - 4.7 2002 - 4.2 (IIRC, he was banged up this season) 2003 - 5.3 2004 - 5.6 4.7 is pretty freaking good for a rookie. While the mobile quaterback does help the running game, a quicker RB would benefit more from a mobile quaterback and increasing by 0.3 isn't too much of an increase from when Young became the starter.
Except VY started playing more midway into Benson's junior year. And his junior year splits are fairly interesting: First 6 games through the OU game (yds / game): 43, 37, 130, 88, 54, 27 Last 6 games: 149, 179, 186, 152, 289, 87 His YPC also went up dramatically in the 2nd half. I don't know exactly when Vince started playing more, but I imagine it was after losing to OU. I think Benson was a product of the Zone-Read system and having a mobile QB that takes attention away from the running back.
He wouldn't be able to get 4.7 yards per carry as a freshman if he was only a product of the zone read. Young did help him some, but it didn't make him a good back as he already was one. Benson was not the best back for the zone read and was better suited for power formations even though his team wasn't. He was banged up his sophomore season. The early part of his junior season he wasn't as good as his freshman year or later in his career. Was this he shaking the rust off or was it Vince Young? Probably a combination of the two.
Hi is still young and has talent. He might make some dumb moves at times, but he is a player that I would gamble on considering that we really don't have a good answer there as of right now.