By Adam Hoge-

INDIANAPOLIS (CBS) — The Bears’ first major acquisition of the offseason is at linebacker.

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With a player already on the roster.

Bears head coach Marc Trestman and general manager Phil Emery confirmed Thursday that Shea McClellin has already made the switch from defensive end to linebacker and will compete for one of the starting jobs at either the strong-side or middle linebacker position.

“Shea has been communicating with (new linebackers coach Reggie Herring), he knows he’s going to be a linebacker,” Trestman said. “He knows we’re going to work with him at the Sam to start, but he should expect to work at both the Sam and the Mike position as he comes back.”

McClellin, the Bears’ first-round pick in 2012, joins second-year players Jon Bostic and Khaseem Greene competing for two linebacker spots. A fourth competitor will likely be added either through free agency or the draft, and that could be free agent-to-be D.J. Williams, who both Trestman and Emery mentioned by name Thursday.

But if the season started today, McClellin would likely be the starting Sam linebacker, with Bostic at the Mike and veteran Lance Briggs at the Will. Fortunately for the Bears, they still have over six months to evaluate the linebacker competition, and both McClellin and Bostic will receive reps in the middle and on the strong-side throughout OTAs, mini-camp and training camp.

“Shea will be used in multiple roles, wherever his skills will take him,” Emery said. “He is a perfect candidate to be on the field all downs in some capacity, whether that is blitzing, rushing, playing against the run in run personnel but he is going to have to compete for his job.”

So why are the Bears confident McClellin can make the position change?

For one, Trestman found that out that Herring’s evaluation of McClellin coming out of college was a positive one — at linebacker.

“Reggie evaluated him and thought he had the ability and the skill set to be a very good linebacker in the National Football League,” Trestman said. “And that was great to hear and great to know. So he’s excited about working with him, and certainly he is as big of an expert as we have on this staff in terms of the ability of developing a linebacker. So we are excited about it.”

The Bears didn’t exactly keep expectations low Thursday, as Emery said McClellin had “no trouble” covering Vikings running back Adrian Peterson out of the backfield last season.

“The guy has very good hips, very good quickness, very good speed for his position,” Emery said. “His size is something that’s rare for us at Sam backer. Nick Roach was our Sam backer. There’s a big difference in size there. He’s going to be the biggest linebacker.”

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Emery said McClellin told him Wednesday that he’s currently at 260 pounds, but they expect him to play somewhere between 242 and 252 next season. And — this is important — both Trestman and Emery stressed that this move doesn’t mean McClellin won’t rush the passer from time-to-time.

“It would be to our advantage to use players who have skills to rush the passer,” Emery said. “I’ll go back. I’m obviously disappointed on the sack production, in terms of that impact, but (McClellin) was our most productive rusher on our team so we want to get him involved in that role, whether it’s from a linebacker alignment, from a two-point or a three-point (stance) or with games and moves and stunts. His athleticism allows him to pressure the quarterback. We want to put him in position where he can make more plays overall.”

Emery isn’t lying when he says that McClellin was the team’s most productive pass rusher last season. According to STATS, McClellin led the Bears with 11 knockdowns and 9.5 hurries. Julius Peppers was second with 7.5 knockdowns and 8.5 hurries.

From the Bears’ standpoint, those numbers show that McClellin can still be an effective player. It’s just a matter of putting him in the best position to succeed. The pressures are impactful — there’s extensive research indicating the average completion percentage of quarterbacks in the NFL drops by nearly 30 percent when they are hurried or knocked down — but sacks are even more valuable, and McClellin only had four in 2013.

“At Boise (State), he played Mike, he played Sam, he played with his hand on the ground. So his versatility is his strength,” Emery said. “I’ll say this: Generally, we’ll take calculated risks, which we did with Shea. When we swing, we’re gonna swing on the high side of athleticism. And that’s why we’re still excited about him being able to contribute at a high level.”

Emery admitted that as he evaluates defensive ends going forward, he’ll “probably make sure they’re a little bit longer and a little bit heavier.” But he values size too and, at linebacker, McClellin is now on the bigger end of his position group.

His skill set also fits the mold of what the Bears are preaching on defense. They want to be versatile, flexible and unpredictable. Trestman said multiple times that the scheme will be built to suit the strengths of the players, not the other way around.

So will McClellin work at linebacker? We won’t know until we see him on the field. But there is something to be said about having a fall-back plan for a first-round pick that didn’t work out at the position he was drafted to play. McClellin was Emery’s first draft pick with the Bears, and like any other personnel move, the pick has served as a learning experience.

“It taught me to keep picking guys that have versatility, because none of us are gonna be perfect,” Emery said. “If you swing and miss on a player, you hope that they have the skill set, that they’re still competing and contributing on your team in a positive way, which Shea did.”

But the Bears know McClellin’s contributions have to be bigger and more impactful.

And they believe those contributions will come at linebacker.

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Adam Hoge covers the Bears for and is a frequent contributor to 670 The Score. Follow him on Twitter at @AdamHoge.