"I call it the ‘Star,'" Saban said.
In that role, Castille moves from his cornerback position to something akin to a third safety, with another corner coming in to make the five-man secondary. Ordinarily a linebacker goes out of the game.
The nickel back is the same position he played last season Castille said following Tuesday's practice. "Just a different name," he said. "We have a position called ‘Money,' too. I'd like to be called ‘Money.' That's part of the dime (six defensive backs) package."
Castille, the son of former Alabama All-America Jeremiah Castille, was a star for Bama last year as a junior. The 6-1, 189-pounder from Birmingham led the Tide with six interceptions and three fumble recoveries. He was fourth on the team in tackles, getting in on 71 stops. He was in on five tackles for loss, had a sack, caused a fumble, broke up six passes, and had three quarterback pressures.
As a defensive back, Castille gets a little more attention from Saban, who works more with the defense than the offense and who has a particular expertise in coaching cornerbacks.
"He does a great job of teaching us the concept of what we're doing and why we're doing it," Castille said of his head coach. Asked if he would miss Saban being "in his face," the player hesitated before answering carefully. "I'll miss it when I'm doing something right and he's telling me that," Castille said. "I won't miss it when I've blown a coverage."
Castille said he is playing more "star" than cornerback, which fits with what Saban said about over half the defensive time being spent in nickel. Castille doesn't make too many mistakes in the new defense. "Surprisingly, I was able to pick it up quickly," he said. "I studied it and learned it pretty well.
"But I still have to open the (play)book and study."
Castille said the new assignments were difficult to learn, "but we've been at it awhile now. We know what to do and we're making some turnovers. I think the first regular defense and the nickel and dime have come along pretty well. "
Castille said that practice consists of the coaches "setting up situations for us – third and long, Red Zone, first and 10, everything you can imagine. And then they run the play they think is best for that situation. When you do what you're supposed to do, you'll make a play. If you have a bust, you give up a play ."
Castille said, "Some guys are smarter than others, and some study harder than others. You have to study. There are so many calls and checks. If you don't know it, you'll get burned.
"It's up to the players. We can capitalize on the opportunity we have here or we can just get by. I think everyone is working hard and we've made a lot of progress."
Castille and his Alabama teammates will practice Thursday, then conclude spring training with the A-Day Game at Bryant-Denny Stadium Saturday. Kickoff is at 1 p.m. CDT.
Castille said visiting fans "may not be able to tell the difference in what we're doing this year and what we did last year." Alabama was in a nickel package most of last season.
"But," Castille added, "for people who know football, they'll see a huge difference. That's not a knock on what we did last year. It's just different."