Maryland assistant coach Nate Clarke keeps an eye on the players during a scrimmage Saturday in College Park. (Jonathan Newton/The Washington Post)

Nate Clarke stood alone near the Maryland football locker room following Saturday’s scrimmage, waiting for his former teammates to finish signing autographs. The Terrapins sat at folding tables along the sideline, wearing full gear as they scribbled their names on memorabilia.

Clarke looked as if he should have been sitting with them. He’s a mountain of a man, a 6-foot-3, 300-pound college student who was once a coveted recruit. He didn’t ask to be a part of the autograph session this year, though; it was just another opportunity for him to come to grips with his new role.

Clarke wore an outfit that befits most college football assistants: a red visor, black pullover and shorts. Part of a long list of Terps who were injured last fall and spring, Clarke suffered a serious leg injury in March and retired from football earlier this summer. But instead of walking away from the team, Clark stayed on as a student assistant, serving as mentor to a veteran defensive line that hopes to be the bedrock of an experienced unit.

“It’s different, but I felt like it needed to happen for me to progress and go on with what I needed to do,” Clarke said. “It’s a love-hate thing.”

Clarke earned a reputation as a hard-nosed player, the type who always felt the pains and aches in his knees but never thought much about it. He was a heralded offensive lineman out of Carroll High in the District and was considered a four-star prospect at guard by Rivals. Clarke played a semester at Fork Union Military Academy before enrolling at Maryland in 2011, and as a redshirt freshman he was moved to the defensive line. He played in eight games as a sophomore last fall and entered the spring as a veteran capable of breaking into the rotation.

“He’s a big, strong man,” Maryland defensive lineman Quinton Jefferson said. “I feel like he was on his up-and-coming before he got hurt.”

But Clarke fractured his left kneecap during a non-pad practice in the spring, and a doctor discovered more cartilage damage that had to be repaired. A surgery that was supposed to be over in 30 minutes instead took four hours. His rehabilitation was projected to be six to eight months. The road back would have been arduous, and he had no guarantee of a starting job. He consulted with Maryland Coach Randy Edsall about his options, then spoke with his grandmother about his future.

“I came up with the decision that this was probably it,” Clarke said. “It was a bad situation, but I saw myself getting through it. Even though this is the sport I’ve played since I was a freshman in high school and I love it, as long as I’m around the sport is enough to keep me going.”

So he accepted Edsall’s offer to help coach, which presents a new set of challenges. Clarke is a soft-spoken. His approach is simple: allow the staff to coach and yell and scream, then slip mentoring into the spaces between. The first day of camp was “weird” because watching players sweat to exhaustion made him feel guilty.

During practice, Clarke stays close to first-year defensive line coach Chad Wilt for much of the drills, offering advice when he notices poor technique or senses a player needs a boost. Last week he pushed a player to be more violent during a pass rush drill. On Monday he advised Jefferson how to use his hands to strike an opponent more effectively.

“He makes us realize how fast we can have it taken away from us,” senior nose tackle Darius Kilgo said. “We don’t want him to get down. We want him to know that we still have his back. He’s still a part of this team.”

Clarke needs just one credit to finish his degree in criminal justice, he said, and he’ll take a class in forensics this fall. He could have graduated in the spring but delayed that so he could be a student assistant. He plans to stay with the team through the spring before he moves on to a possible career in law enforcement.

He has won respect with his new role, he said, but it won’t come without some difficult moments. He felt odd watching his former teammates don their uniforms before the scrimmage and after, when he hung out in the background while the players signed autographs.

“It’s just a different scene, a different adjustment, but I just love being around the players and being around everybody,” he said. “That’s what I really miss the most.”