He is not dedicated. His knee injury was supposed to sideline him for a month at max, and it ended up keeping him out about half the season.
Yeah, that's kinda what I was getting at with the moody comment. He strikes me as a guy that's not very 'excited' about playing baseball. He's doing it because he can...not for the love of the game. If he gets on a role he'll be fine but when he gets down (or especially if he gets hurt) he really doesn't have the fire to make him fight his way back.