Defensive lineman Mitch Unrein is a big part of the Bucs' efforts to improve their run defense, and while sacks are what get headlines, he's stayed in the NFL for seven years by doing the dirty work against the run.

"I've always tried to hang my hat on being a good run defender, a run stopper," said Unrein, who turned 31 last week. "Early on in my career, a veteran guy told me 'If you can stop the run really well, you can play in this league for a long time.' I kind of took that to heart, and I've always taken pride in that."

The 6-foot-4, 301-pounder signed a three-year deal averaging $3.5 million a year, more than double his annual salary at any point in his career. He said he still plays like an undrafted free agent, something he's seen in another new defensive tackle in Philadelphia's Beau Allen.

"We've had chips on our shoulders, and that's something we're going to keep building on," said Unrein, who went to dinner with Allen when he visited Tampa during free agency. "We're going to feed off each other, and also push the other guys to reach their full potential. I'm looking forward to getting in there and working with them."

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Unrein — pronounced UN-rhine — is listed as a defensive tackle, but played most recently as a 3-4 end in Chicago, having played most of his career as a 4-3 tackle who can step outside when needed.

"In Chicago, I played mainly 5-technique as a 3-4 end, but I could also bump out to 6 depending on the call," he said. "I've played nose, zero-technique, shade, 1-technique, 3. I've always said if you have the right footwork and handwork, you can play anywhere down the line as long as you're good at recognizing blocks and schemes. You don't have to be the biggest guy to play inside as long as you have good leverage."

Unrein said his decision came down to staying with the Bears or going to Tampa Bay, which had courted him from the start in free agency.

"It kind of whittled down to Tampa Bay and Chicago," he said. "I just felt like Tampa Bay was a much better fit for me. I had a great time in Chicago. I just felt like the way things were going, the upside for the Tampa Bay Buccaneers was a lot better than the Chicago Bears."

Unrein came into his own in Chicago — after three starts in his first five years in the NFL, he had 21 in three years with the Bears, playing for the same defensive line coach (Jay Rodgers) he had in Denver from 2012-14.

"You get more confidence, you get more experience," he said. "The game slows down for you each and every year that you're in the league, just recognizing plays and things like that. That's something where I took a step forward, recognizing plays and formations, something that comes with experience."

Unrein had 2.5 sacks last year, and has just 4.5 for his career, but said he's never been about piling up sacks so much as putting his teammates in position to do that by setting up predictable passing downs.

"I know getting after the quarterback is a huge thing in the NFL," he said. "Guys get paid a lot of money rushing the passer. But first things first, you have to be able to stop a team from running the ball on first and second down in order to let those guys get out there and get all the sacks."