Late in a 17-13 loss at Tennessee, Castille was upended by a Volunteer defensive back. The hit was clean, but the damage was critical: torn anterior cruciate and lateral collateral ligaments in his right knee.
A year later, Castille is back in the Alabama lineup, but his impact has been minimal, thanks to the emergence of fellow fullback Le'Ron McClain and the fact that his knee simply isn't as healthy as it could be yet. He also sprained his ankle during Saturday's victory over Utah State, further marring the year.
Through eight games, Castille's production has slipped somewhat. He has 36 carries for 81 yards (fewer than even Tyrone Prothro) and six touchdowns, scored in goal-line situations.
He has seven receptions for 35 yards, far fewer than McClain, who has 12 catches for 92 yards and two touchdowns.
He isn't upset, though, for two reasons: Alabama is 8-0, and he's contributing. Those are two things few would have expected late last fall.
"It's good and bad," Castille said of his current status. "You'd love to play more, but I'm giving my knee the opportunity to actually rest a little bit.
"I'm not taking as many shots. It won't come to true form until next year, when it's completely same as my other one, where I'm at right now."
Castille readily admits this hasn't been the easiest season for him to deal with. Tailbacks Kenneth Darby and Glen Coffee have played well, and McClain has developed into one of the SEC's best fullbacks.
The crowded backfield, coupled with the passing game's return to prominence thanks to a healthy Brodie Croyle, has marginalized Castille.
"That's just how it's come out," he said, showing no signs of anger at the development. "Le'Ron's been playing excellent, and there's no need to take him out. We've got two great tailbacks and I've had to find my role."
Luckily for Alabama's locker-room karma, Castille is perfectly happy to take his time doing so.
He knows that he's part of something special.
And with an offseason of true training ahead, he can concentrate on helping Alabama to a great ending – then write his own special ending next year.
"There's nothing I'd like better," he said of a strong senior year.
"We just beat Tennessee, we're (8-0), taking the time to do it right. I'd like to come back next year and contribute a little bit more.
"When the season's over, I'm really going to get back in the weight room like I want to, get my leg back to where I really want it to be. I'm really looking forward to that, but for now I just want to finish up strong."