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Perhaps it makes sense, even in the NFL, that a man who goes by “Tank” has had trouble finding a good fit.

A 2013 second-round pick by the 49ers, Tank Carradine didn’t really settle in with the team that drafted him. He was cast as a defensive tackle and outside linebacker but took to neither, nor in four seasons did he replicate the high sack numbers as a pass rusher he’d posted at Florida State.

Last season, Carradine seemed to find a niche as a run-stopping defensive end. Then, in Week 3, he incurred a high ankle sprain that sidelined him for the next eight weeks.

That the 49ers opted not to re-sign him in free agency came as little surprise to Carradine, who signed with the Raiders in March and is hoping to build on the promise of his 2017 under head coach Jon Gruden and defensive coordinator Paul Guenther.

“I feel like my time there (with the 49ers) kind of ran out,” Carradine said last week. “I feel like everything went along good, but I didn’t have the success I wanted. I felt like I was in different schemes and couldn’t find the right scheme that actually fit me. And then when I actually found a scheme that fit me, I ended up getting hurt.

“So I couldn’t really have that full season to show what I do. But so far, I’m here and I’m excited to be with the Raiders and excited to come out here and play with these guys.”

When the 6-foot-4, 270-pounder played well last year, it was largely as a six-technique — lining up over the tight end and defending against the run. With All-Pro defensive end Khalil Mack absent amid a contract holdout, Carradine has played that role on the Raiders’ first-team defense and also has gotten work as an inside pass rusher.

“This is a good football player,” Gruden said. “We like him as a six-technique particularly, head-up on the tight end. Very hard-nosed run defender with some pass rush ability. He’s done a nice job for us.”

Carradine recorded 11 sacks in his final season at Florida State. In 44 games with the 49ers, including eight starts, he totaled 5.5 — with three of those coming as a rookie in 2014.

Still, Carradine said he believes he can make a mark as an interior pass rusher. And that happens to be an area of serious need for the Raiders, who were 24th in the NFL last season in sacks (31) and are hoping to take some pressure this year off edge rushers Mack and Bruce Irvin.

“The coaches, I’m excited that they give me the opportunity to be able to get down there and get on the guard and get some one-on-ones and be able to get to the quarterback,” Carradine said. “That’s something that I feel the 49ers didn’t really give me an opportunity to do. And I’m excited that they’re giving me an opportunity to do that.”

Carradine’s current role with the starters is tenuous, given that Mack is expected to return at some point. In that sense, it would behoove Carradine to show he can also make an impact on the inside.

The Raiders’ group of inside pass rushers includes rookies Maurice Hurst and P.J. Hall, Treyvon Hester (zero sacks in 2017) and Mario Edwards Jr., a former Florida State teammate of Carradine’s whose first few seasons have been underwhelming. Aside from Edwards (3.5), Justin Ellis (0.5) is the only returning defensive tackle who recorded a sack last year.

Carradine said last week he “can’t wait to have (Mack) back.” In the meantime, he’s using his added reps to “get the defense down and help some of the younger guys pick up some stuff.

“Whatever role they give me, I’m going to play the role and I’m going to do my best to help the team win. Excited to play with (Mack) and be out there with him and Bruce.”

In his early career with the 49ers, Carradine bulked up to nearly 300 pounds to withstand the demands of playing defensive line in a 3-4 scheme. He later shed the extra weight without, it seems, sacrificing strength. Albeit before the Raiders donned pads in camp, All-Pro left guard Kelechi Osemele said Carradine “has a good bull rush” — also fitting for a man dubbed “Tank.”

“Tank’s a physical player in there,” Guenther said. “He’s smart. He’s understanding our defense — all the different blitzes and coverages and fronts that we’re running. He’s been a real good surprise for us.”

Matt Kawahara is a San Francisco Chronicle staff writer. Email: mkawahara@sfchronicle.com Twitter: @matthewkawahara