I think he has the potential to be really good before his BYU career is over, but he strikes me as very similar to Romney, so I'm not sure how big of an impact he's going to have as a true freshman. I seems to recall he wants to play a year and then go on a mission.

As for elite RBs... don't hold your breath. We'll very likely rely on RB by committee for yet another year, and the run game will be solid, but not great.