By Chris Emma-

LAKE FOREST, Ill. (CBS) — When you think of Jared Allen, a certain image comes to mind.

READ MORE: Chicago Weather: Rounding Out The Warmest Weekend Of The Winter

It’s the imposing pass rusher getting to a quarterback with a vengeance, then unleashing his trademark sack dance. Allen has 134 sacks in his 11-year NFL career as a defensive end, including an impressive 22 in 2011 with the Minnesota Vikings.

The Bears’ version of Jared Allen is different. He had just 5.5 sacks in a disappointing first season with Chicago in 2014.

Now, Allen has a new job description under new coach John Fox and defensive coordinator Vic Fangio: 3-4 outside linebacker.

“I might have the best athletic feet in the history of the world,” Allen joked after Tuesday’s mini-camp at Halas Hall.

Allen, who turned 33 on April 3, appeared to be himself again, cracking jokes and a smile with teammates and reporters. This wasn’t quite the case a year ago in his first season as a Bear.

The turmoil surrounding a broken locker room and the inevitable departure of coach Marc Trestman brought a negative feel around Halas Hall. Players were walking on eggshells, even the jovial Allen, and the Bears finished with an abysmal 5-11 record. Change became a good thing.

“Sometimes, when you go through just misery, you see the light,” Allen said.

“I’ll be real honest: Mentally, I had never really experienced that in my career. I had to own that. I told the guys, that wasn’t me.”

The recent reality became that Allen has three more years left on the deal that he was given by former general manager Phil Emery, and he may not be a fit for the Bears’ new schemes, which require more agile edge rushers who can drop into coverage.

Fox denies that Allen playing outside linebacker is shoving a square peg into a round hole.

READ MORE: MISSING: Khoshaba Dikyanos, 84, Last Seen In Lincoln Square

“You try to find good human talent at all levels, upstairs and downstairs, and you go about your business,” Fox said.

Part of why Allen feels rejuvenated this season is the learning process. He embraces the opportunity to play linebacker and learn an entirely new position and its roles within a complex system.

Allen has spent long hours in the Bears’ playbook while picking the brains of teammates Lamarr Houston and Pernell McPhee. He has also studied film of some of the NFL’s best 3-4 outside linebackers, such as Aldon Smith and DeMarcus Ware, watching their movement off the line and — more importantly and differently for Allen — their steps into pass coverage.

“This is like college football again, just learning a whole new system,” Allen said. “I’m at home studying the playbook, and I haven’t done that in 10 years.”

One of the greatest differences for Allen is reading the entire offense, not just the line. He gets keys from the defensive tackle and calls from the middle linebackers.

Allen is maintaining his same playing weight of 255 pounds, something which the Bears’ coaches recommended. However, almost everything else with his role is different.

“It’s a little bit new for Jared,” new Bears safety Antrel Rolle said. “He’s a playmaker, man. Primarily, he’s a guy that gives a quarterback hell, but for the most part, he’s a very versatile guy.”

Football followers will think of Allen as that mean sack man with the notable celebration. After all, he’s made a career of getting to the quarterback.

A new season, position and opportunity in Chicago has Allen feeling rejuvenated.

“To be back challenged mentally and be a part of something that is bigger than just individual — it’s truly a team — the energy is just different here,” Allen said. “It’s really cool just to walk in here.”

MORE NEWS: Chicago Speed Cameras To Start Issuing $35 Tickets To Drivers Going 6 MPH Over The Limit On Monday

Follow Chris on Twitter @CEmma670.