ALLEN PARK >> Four of the top five linebackers on the Detroit Lions’ depth chart entering this season are now on injured reserve.

While the team has found success backfilling that position with depth pieces, one can’t help but wonder if that same success would still be had without Jack Campbell, the second-year man out of Iowa who was born to lead. Not only has his play seen a massive jump, but his leadership has, too.

“Man, he’s a rock,” Lions defensive coordinator Aaron Glenn said this week.During the spring, Detroit’s coaches raved about Campbell’s grasp of his responsibilities within Glenn’s defense. Alex Anzalone missed significant time during OTAs and minicamp, allowing Campbell to wear the green dot (calling plays for the defense). As the depth chart behind him has become a revolving door, Campbell’s ability to bring the newbies along has gone a long way.

“If you had a picture of a MIKE linebacker, he would be probably standing in front, because of how he operates,” Glenn said. “He’s a man’s man. He loves standing in front of the huddle to give the call out to those guys and they really, really respect him. They respect him because of how he is personally, but they respect the way that he plays the game.”

This season, Campbell has played 84% of defensive snaps for Detroit’s defense. Following his last game against the Chicago Bears, he’s now at 1,300 defensive snaps for his career. All told, the leadership role he’s now been thrust into due to injuries to Alex Anzalone, Derrick Barnes, Jalen Reeves-Maybin and Malcolm Rodriguez is probably not something he would’ve been able to handle as well in his rookie season.

“Do I think I could’ve done it as well as I’ve done it right now? Probably not,” Campbell told The Detroit News. “Where I’m standing today, I’ve had way more experience, way more games, another training camp, spring OTAs, just to learn the whole system, so I feel like I probably … (am) more detailed this year than I would’ve been last year.”

Lions head coach Dan Campbell said Jack Campbell is “more mature” in his second season.

“He’s older, he’s more developed, time on task, game slowed down for him, and then on top of that he was always a pretty headsy player, pretty smart, instinctive guy, and so with, that’s boded well for him,” Dan Campbell said. “He’s got a ton of reps, man, in a two-year period, that’s good. Honestly, he’s kind of the guy — the more you put on him, the better he gets, I feel like. He’s one of those, so he’s doing well right now. We’re going to ask a lot of him again.”

This season, Campbell has 90 tackles in 12 games — just shy of the 95 combined tackles he posted in 17 games as a rookie — with three pass defenses, 1½ sacks and five tackles for loss.

“It’s 100 miles per hour all of the time, even in walkthrough,” Glenn said. “He’s going through his reads and he’s going through his drops. He’s making sure that he’s fed up on the ball the right way, bent knees, ready to get ready to strike, and it’s just who he is.

“He has been a rock for us and I’m glad that we have him.”