The Chicago Bears have been lucky to have legends like Bill George, Dick Butkus, Mike Singletary and Brian Urlacher hold down the middle linebacker position in the team's 4-3 defense over the years, but with the Bears moving to a 3-4 defense this offseason, the team is now looking for two inside linebackers who can control the middle of the field in defensive coordinator Vic Fangio's scheme.
During Fangio's time in San Francisco, he helped turn Patrick Willis, NaVorro Bowman and Chris Borland into some of the league's best inside linebackers, and he is viewed by many as one of the league's best defensive coordinators.
"I think he’s one of the all-time best defensive coordinators in the history of the league," said former 49ers head coach Jim Harbaugh, according to Greg A. Bedard of The MMQB. "I think that’s who he is. I think that’s what his legacy will be someday."
Chicago struggled mightily on defense in both 2013 and 2014, and Fangio knows he has a tough task ahead of him, saying, according to Larry Mayer of ChicagoBears.com:
It was told to me early on when I got here that they’ve given up more yards and points the last two years than anybody in the league, so we’re going to have to make our own building blocks. But I think any time you come to a new place, the first job is to make the players you already have better. That’s our job No. 1, before you talk about free agency and the draft and whatnot. So we need to make the guys that we have here better.
Linebackers Mason Foster, Jon Bostic, Shea McClellin and Christian Jones are all set to compete for a starting role at inside linebacker in Fangio's defense this offseason, but in order to project who will be the starters in 2015, we have to understand what Fangio expects from his inside linebackers.
Inside Linebacker Role in Fangio's Scheme
In a traditional base 4-3 defense, the middle linebacker position is responsible for plugging up holes in the running game and covering tight ends in the middle of the field.
When Lovie Smith implemented the Cover 2 defense in Chicago, the middle linebacker position took on more responsibilities with Urlacher at the helm. Because of Urlacher's athletic prowess, he was asked to not only defend against the run, but also drop back and cover the middle half of the field, almost like a third safety.
In basic terms, a 4-3 middle linebacker is expected to be tough enough to step up against the run, but also agile enough to drop back in coverage. In Fangio's 3-4 defense, one inside linebacker is expected to be a force against the run, while the other is expected to be a jack-of-all-trades who can play against the run, rush the quarterback and drop back in coverage.
The more traditional run-stopper in Fangio's defense is referred to as the "Mike" linebacker, while the jack-of-all-trades linebacker is referred to as the "Jack" linebacker.
In the past, Willis played the run-stopping Mike linebacker role in Fangio's scheme, while Bowman played the Jack linebacker spot. Fangio prefers both his inside linebackers to be above-average athletes, and even though the Jack linebacker is expected to be more of a freelancer in terms of his assignments, he still has responsibilities against the run.
While Bostic, McClellin, Jones and Foster all have their flaws, their athleticism is considered to be above average for the position.
As it currently stands, two linebackers appear to be the front-runners for the position, but a pair of wild cards could push for a starting role in training camp later this summer.
The only inside linebacker the team added in free agency this offseason was Foster, and he is currently one of the front-runners to hold down a starting spot in 2015.
Foster was taken in the third round of the 2011 draft by the Tampa Bay Buccaneers and started 57 games at middle linebacker over the course of the last four seasons. For his career, he has registered 343 tackles, six sacks, 12 pass deflections, five interceptions and has scored two defensive touchdowns.
He spent his entire career in Tampa Bay playing in a 4-3 defense, but he said he chose to come to Chicago because of the 3-4 defense.
"The main reason why [I chose] Chicago was definitely the 3-4 scheme," Foster said on SiriusXM NFL Radio, via Mayer. "It’s something that after getting into the league I wanted to be a part of playing a 3-4 system. I think it fits my skill set, giving me a chance to make plays."
Foster has the ability to step up against the run, but he is also athletic enough to drop back in coverage. His best fit in Fangio's 3-4 defense is at the Mike linebacker spot, but he is versatile enough to play the Jack linebacker position if needed.
"I don't think people realize how smart he is," former Buccaneers general manager Mark Dominik said about Foster, according to Ross Jones of Fox Sports. "He really does understand defenses. He can make the calls, get guys lined up. That's a very valuable thing when you look at middle linebackers."
Given Foster's history as a starter and the ability to play both the Mike and Jack positions, he stands the best chance of being a starter at inside linebacker come Week 1.
With Foster likely penciled in as one of the starters on the inside, Bostic appears to be the other front-runner at the position.
Selected in the second round by the Bears out of Florida in 2013, Bostic was thrust into a starting role his rookie season and finished with 57 tackles, two sacks and one interception. He moved from middle linebacker to strong-side linebacker last season and finished the year with 84 tackles and three pass deflections.
Injuries forced him to jump around last season, and he ended up playing nine games at middle linebacker and two games each at strong-side linebacker and weak-side linebacker, according to Pro Football Focus.
He missed three games last season due to a back issue, and he did not participate in the team's first minicamp practice late last month, according to Adam Jahns of the Chicago Sun-Times:
Even though he has struggled at times during his first two years in the league, he remains a front-runner for the position because of his experience playing in a 3-4 defense while at Florida.
He was terrific against the run for the Gators, but he has struggled in the NFL with his anticipation and timing. After an abysmal year against the run in 2013, he did show improvement last season.
According to Pro Football Focus, Bostic finished with a minus-14.0 grade against the run in 2013, but he finished with a plus-4.6 run grade in 2014. Last season, he played 153 snaps against the run and finished with 24 tackles, and his 9.2 run-stop percentage was 18th best among all inside linebackers in 2014, according to Pro Football Focus.
Bostic may be able to thrive in Chicago's 3-4 defense as a two-down run-stopper next season alongside Foster, but even though he appears to be a front-runner right now for the position, both Jones and McClellin have a chance to earn a starting job this summer.
The Wild Cards
While Foster and Bostic appear to be the front-runners at the position, Fangio believes both McClellin and Jones have the ability to make an impact in his defense, according to Chicago Bears radio network sideline reporter Zach Zaidman:
Earlier this offseason, the Bears opted to move McClellin to inside linebacker, and head coach John Fox thinks the former Boise State star is a good fit on the inside.
"I thought highly of him when he came out of Boise State, [but] he was more of an outside linebacker in that scheme," Fox said, according to Jahns. "Right now, putting him inside, we’ll see how he does there, see how he progresses, because he is a good athlete. He does have good size, good length."
McClellin began his career in Chicago as a 4-3 defensive end in 2012, but he moved to strong-side linebacker last offseason. He excelled as an outside linebacker at Boise State, and Fangio thinks McClellin's growth has been stunted in the NFL because of his position changes.
"He’s got good size, he’s got good athletic ability, I think," Fangio said, according to John Mullin of CSNChicago.com. "He has been hindered, I think, by being moved around. To no fault of anybody’s, just the way it goes."
McClellin registered 36 tackles last season, but he struggled against the pass and will have to prove once again this offseason he can adapt to a new position.
"I’m just trying to get used to the calls, get used to the fits," McClellin said, according to Jahns. "It’s a different defense, a 3-4 now. I have to get used to that kind of thing, but it will be good."
He moves well laterally, but he struggles to read and diagnose plays. He could potentially earn playing time as the Jack linebacker because of his athleticism and ability to rush the quarterback, but he will have to show consistency this offseason in order to grab a starting job.
Like McClellin, Jones is making the move to inside linebacker this offseason, and Fangio likes what he has seen from the former Florida State Seminole.
"He’s got good size. He’s got good athletic ability," Fangio said, according to Arthur Arkush of ChicagoFootball.com. "He’s a young, eager guy and football’s important to him. I think he’s got a bright future if he can develop."
Jones went undrafted last year, but he played in all 16 games and finished the season with 69 tackles and two sacks. After making two starts in the middle of the season, Jones started the final three games of the year and registered 31 tackles while playing weak-side linebacker.
Jones is a fluid linebacker who moves well from sideline to sideline, but he also has the ability to apply pressure up the middle as a pass-rusher. He needs to improve in pass coverage, but he has the potential to grow as a player under Fangio.
McClellin and Jones are not the front-runners to be starters this season, but they both have a chance to claim a spot in the starting lineup with a strong training camp.
There will be competition at a number of key positions this offseason in Chicago, but the battle for the two open inside linebacker spots may end up being the most competitive.
Foster, Bostic, McClellin and Jones all have a chance to be named one of the starters for Week 1 against the Green Bay Packers, but only two will sit atop the depth chart after training camp concludes.
Because of his experience and productivity over the years, Foster stands the best chance of holding down the Mike linebacker spot in 2015.
The fiercest battle in training camp will come down to Bostic, McClellin and Jones at the Jack position. Bostic and McClellin both have upside and potential, but Jones proved in a limited role last season he can be productive against both the pass and the run.
McClellin and Bostic could see some playing time in certain sub-packages, but Foster and Jones look to be the best fits in Fangio's 3-4 defense at the Mike and Jack linebacker positions in 2015.
Statistical information courtesy of NFL.com unless otherwise noted.
Matt Eurich is a Chicago Bears Featured Columnist for Bleacher Report and a member of the Pro Football Writers of America.