UNIVERSITY PARK - Bill O'Brien said he thinks about the unit "24/7," so it's clearly an area of concern for the Penn State coach this fall.
Is it the offensive line? No.
The new quarterback? No.
Those are all the usual question marks each season for the Nittany Lions, but O'Brien has a surprising area to worry about this year.
It's the linebackers, an oddity given that the Lions have produced one star player after another for the past decade.
"Whenever it's your turn to step up, it's go time, it's your time to shine," junior Mike Hull said. "And I'm ready to fill that spot and help our defense this year."
O'Brien isn't worried about Hull playing well as a first-year starter on the outside. The coach also has spoken several times about senior middle linebacker Glenn Carson being underrated, and he has high hopes for redshirt freshman and projected starter Nyeem Wartman.
The Lions appear to be in good shape in the starting unit, but as O'Brien has lamented several times, the lack of depth at linebacker is the reason for his concern.
"I think our three linebackers that are in starting spots right now, I believe that they are very, very good players," O'Brien said this past week. "They're tough guys, they're smart guys, and they're instinctive players."
With those three on the field together, Penn State probably will have few linebacker concerns. But if one or more of them get injured or need to be spelled, the Lions will have to turn to inexperienced, unproven backups to play major roles.
The primary backups at this point are redshirt freshmen Gary Wooten and Adam Cole, along with redshirt sophomore Ben Kline, who's sitting out spring drills after undergoing shoulder surgery.
"We certainly have to do a good job the rest of the spring and obviously over summer and into training camp of making sure that Carson, Hull and Wartman are as healthy as they possibly can be going into the opener," O'Brien said.
Carson was overshadowed by standouts Michael Mauti and Gerald Hodges last year but still had a solid season with 85 tackles (40 solo), three tackles for loss and one sack. He will have a chance to be the guy in the linebacker unit this season and earn the credit O'Brien believes he deserves.
"Obviously that's what I'm working toward, and I feel that I can fill that role," Carson said.
To do that, he will be focused on making more big plays.
"We kind of pride ourselves as linebackers to attending to detail and the little things," Carson said. "[That] is what's going to make you take the next step up - not missing tackles and instead of knocking down a ball, making that interception, making a play. That's something I'm really looking to do is make some bigger plays, take some more shots, make some more tackles for loss."
Hull gained a lot of attention last year when it became public he considered transferring to Pitt after the NCAA sanctions. Penn State is fortunate he stayed.
Hull played very well in a backup role, finishing with 58 tackles (34 solo), four sacks, five tackles for loss and two fumble recoveries. His highlight was a 74-yard fumble return for a TD against Navy.
"I've just been in the film room a lot, working really hard in the offseason workouts, and I'm ready to step up and be a leader and help the defense," Hull said.
Hull played a lot as a backup but will be counted on to be on the field for entire games this year. He's been concentrating on his conditioning in order to achieve that goal.
"Me and Glenn haven't really played much together," Hull said. "But we know the defense, we've been in the system for a year, and everything's going real smooth right now."
Hull saw the intensity and leadership Mauti and Hodges played with last year and plans to play the game the same way. He also knows how important it is for players like him, Carson and Wartman to carry on the great tradition of Linebacker U.
"It just motivates all of us to keep working toward the tradition [previous stars] left for us," Hull said.
Wartman played in two games last year before suffering a season-ending knee injury. He was able to get a medical redshirt, so he still has four years of eligibility.
The fact that Wartman has emerged as a projected starter coming off the injury is a testament to his skills and potential.
"I see a lot of athleticism in Nyeem, and plus you can see he's very physical sometimes taking on blockers and things like that," Carson said.
It's up to Carson and Hull to help mentor Wartman and the other young linebackers, just as the long line of PSU standouts have been mentored by the players who came before them.
"Nyeem's looked good so far," Hull said. "He's doing a great job coming in, and I think he's going to be a great player for us."