Bears’ linebackers must make up for departures

Cal’s inside linebackers refer to themselves as the “Tone Setters.”

The group found themselves trying to alter a subdued setting Wednesday night, when head coach Justin Wilcox announced that junior inside linebacker Gerran Brown had been forced into a medical retirement.

“He could have been a key to our team this year,” junior inside linebacker Evan Weaver said of Brown, who was fourth on the team with 61 tackles last season. “It just creates opportunities for the younger guys. … It’s going to create an opportunity for those guys to show up before they even thought they might have touched the field.”

The Bears’ inside linebackers already had the formidable task of trying to replace Devante Downs, who was a contender for the conference’s defensive player of the year with 65 tackles, three sacks, two interceptions, two forced fumbles and two fumble recoveries before suffering a season-ending injury in the seventh game last year.

Now, the group’s only experienced players are senior Jordan Kunaszyk and Weaver, who were productive as Cal generally used a four-man rotation at the two inside linebacker spots last season.

That leaves a bunch of newcomers: junior-college transfers Colt Doughty and Tim Newman and six freshmen. Wilcox said the staff will consider adding depth by moving some outside linebackers inside and is exploring packages that utilize three safeties at a time.

Brown went down toward the end of a practice last week, but returned to the sideline the next day without a noticeable limp and only a thin brace on his knee. Wilcox, however, said the undisclosed injury that forced retirement predated that sequence.

“It’s a really tough deal,” Wilcox said. “Gerran is a warrior. He loves the team, loves football and wants to do it. … I feel for him. It hurts. It hurts him really bad.”

Brown has remained a fixture at practices, offering advice to freshmen Zach Angelillo, Louie Bickett and Evan Tattersall and often identifying the offense’s plays before the snap.

“He’s one of the smartest guys on the field. He’ll call out everything,” sixth-year senior tight end Ray Hudson said. “On offense, we hate him, because we line up for a play and he knows every route. …

“Knowing how strong he is, he’s not going to look at in a bad light. He’s going to make the best of the situation. He’s going to help out these young guys. He’s going to make that position group grow, because he’s going to pass on that knowledge.”

Brown was a bit of an unknown when he transferred from Washington in January 2017. Eight months later, he had worked himself into the rotation, and by the season’s final month, he had earned a starting spot alongside Kunaszyk.

Kunaszyk, a video rat who racked up a teamleading 74 tackles last season and emerged as the defense’s leader this offseason, and Weaver, a converted defensive lineman who is a downhill-oriented player, make a nice complement to each other in Cal’s 3-4 scheme.

But no one expects them to be able to play 80 snaps per game.

“I’m not worried,” Weaver said. “I think I was born to play football, so I’m really not worried about it, at all.”

Rusty Simmons is a San Francisco Chronicle staff writer. Email: rsimmons@sfchronicle.com Twitter: @Rusty_SFChron