Tracy Rocker was a successful college defensive line coach. So why did he decide to join the Eagles’ staff?

Tracy Rocker has spent the bulk of his coaching career working with what the NCAA likes to call student-athletes.

Over the last 25 years, the former Outland Trophy and Lombardi Award winner at Auburn has coached the defensive lines at nine schools, including six in the Southeastern Conference.

In January, Rocker, who was inducted into the College Football Hall of Fame in 2004, was only a week into yet another college job at his alma mater when he got a call from the Eagles’ new head coach. Nick Sirianni wanted to talk to him about the defensive line job on his staff.

Rocker’s only previous NFL coaching experience was a three-year stint as the Tennessee Titans’ defensive line coach from 2011 to 2013. He also played in the league for two years with Washington.

Given his age — he turned 55 in April — and his comfort level with the college game, you might think Rocker would have preferred to continue tutoring those student-athletes. But the lure of the NFL is strong.

“This is one of the ultimate jobs out there, at the highest level of football,” Rocker said Wednesday, pretty much echoing what Eagles quarterbacks coach Brian Johnson said a day earlier about his decision to bolt the SEC (Florida) for the NFL. “So, it was a very easy decision to make.”

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Rocker is the Eagles’ fourth defensive line coach in the last four years, replacing Matt Burke, who replaced Phillip Daniels, who replaced Chris Wilson. He inherits a unit that was the motor to a pass rush that finished third in the league in sacks last season (49) and recently added four-time Pro Bowler Ryan Kerrigan.

But Kerrigan, who has 95½ sacks in 10 NFL seasons, will turn 33 in August, which is the same age that Brandon Graham turned in April.

Six-time Pro Bowl defensive tackle Fletcher Cox is 30, and, while he bristles at suggestions that he too is getting old, the truth is his play has slipped since his All-Pro year in 2018, when he was one of the two best interior linemen in the league.

There’s also the matter of Derek Barnett, who is in the option year of his rookie contract. Barnett, who was the 14th overall pick in the 2017 draft, hasn’t lived up to expectations.

Part of that has to do with injuries. Barnett, who broke Reggie White’s sack record at the University of Tennessee, has missed 15 games over the last three seasons. But even when he’s been healthy, he hasn’t been the kind of dominant player you hope you’re getting with the 14th pick in the draft. He has just 19½ sacks in four seasons.

In the three years Rocker spent with the Titans, they finished in the top 20 in the league in sacks only once.

Asked about the difference between coaching college and pro players, Rocker said: “In college, you get kids at a lot younger age, and there’s a bit more [need for] developmental growth there. Not just on the field but off it.

“In the NFL, we assume they know everything because we gave them money. But it still requires a little bit of conversation about rookie development. As a coach, I feel my job is to approach every day the same way. I try to help them improve their game so that they can be successful. And also because we need them to help us win.”

NFL Network analyst Brian Baldinger, who spent 12 years in the league as an offensive lineman, said it’s going to be important for Rocker to develop some of the younger players, including Barnett and Josh Sweat, as well as rookies Milton Williams and Tarron Jackson, and others.

“What you have to do with those [defensive line] guys is exactly what Stout [offensive line coach Jeff Stoutland] does with the offensive line,” Baldinger said. “These guys have to work at learning moves and countermoves and how to get off blocks and how to recognize blocks.

“The college game is so much different from the pro game. Even a guy like Fletch. Everybody loves Fletch. He’s still a very valuable player. But he never really learned how to rush the passer. Not like Aaron Donald. He’s just been playing off his God-given ability, which is tremendous.

“But to me, a defensive line coach needs to develop these guys and get them to improve. Are they going to learn a cross-chop? Can they learn a rip-club? Can they put moves together?

“I see Stout develop these [offensive line] guys. I see him take Jordan Mailata, who didn’t even know how to line up in a stance when he was drafted, and turn him into a productive starter. But I really haven’t seen anybody develop these defensive linemen outside of their own innate abilities.

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“That’s what I would hope you get from a defensive line coach. I want to see if Tracy Rocker can develop any of these guys.”

Rocker has some common ground with Barnett, if only conversationally. He was the defensive line coach at the University of Tennessee the three years after Barnett left.

“I’ve really enjoyed Derek,” Rocker said. “I missed him on his way out, but I saw him play throughout the SEC [he was at Georgia when Barnett was playing for the Vols]. When I got to Tennessee, the first thing I heard about Derek was everybody said what a great person he was. And such a hard worker. After meeting him, it’s the same person [they described].”

“If we’re backed up, do we need to be disruptive, or do we need to key the ball? Those are things that are important to me as a coach. There’s a time and place for everything.”

It still unclear whether the Eagles’ new defensive coordinator, Jonathan Gannon, wants his defensive line to be as aggressive as his predecessor, Jim Schwartz. Schwartz’s defense was a downhill operation. Shoot first. Ask questions later.

Rocker said Wednesday that Gannon’s defense is going to be an attacking one but added: “You also have to understand it’s not just one thing. What about situational football? Situational awareness? You’re not going to run the red light. Sometimes it’s about playing the play, understanding where you’re located on the field.

“If we’re backed up, do we need to be disruptive, or do we need to key the ball? Those are things that are important to me as a coach. There’s a time and place for everything. But I feel like we’re going to have to read at times. We’re going to have to be disruptive at times, but sometimes you have to react. We’re defensive players, so we’re reactionary. That’s what we do.”

Rocker will have something else besides football to think about next month before the start of training camp. His son Kumar, who is a pitcher at Vanderbilt — of course he went to an SEC school — is expected to be one of the top five or six players taken in the Major League Baseball draft July 11-13.

“I’m more of a dad,” Rocker said. “That’s what he does, and I’m proud of him. I’m supportive of him. I’m just trying to be a dang good dad and guide him in the right way.”

Kumar Rocker, who is a massive 6-foot-4, 255-pound right-hander, played football when he was a younger but preferred baseball.

“I thought he was a very good football player,” Rocker said. “I wish he would have played for me. But he chose the right spot for him, and I’m proud of him.”