MINNEAPOLIS -- Given the struggles of Minnesota's starting rotation, it's no surprise that Twins relievers combined to throw more innings than other team by a wide margin in 2013.

The bullpen accounted for 579 1/3 innings, which was nearly 25 innings more than the Rockies, who logged 555 2/3 frames from their relievers to rank second behind the Twins.

So given the workload, it makes what the bullpen accomplished even more impressive, as Twins relievers combined to post a 3.50 ERA that ranked fifth in the American League. The relief corps also ranked sixth in the Majors with both a 1.22 WHIP and a 2.75 strikeout-to-walk ratio.

"We overtaxed our bullpen but the bullpen was good this year," Twins general manager Terry Ryan said. "That held up under the circumstances."

The Twins can count on many of the same bullpen arms next season, as only Josh Roenicke is a free agent after being outrighted off the 40-man roster in October because of his late-season struggles. Relievers Brian Duensing and Anthony Swarzak are both eligible for arbitration but likely to be tendered contracts.

As a result, the Twins don't need to be aggressive in free agency to sign high-profile relievers, but the club is always on the lookout to upgrade the 'pen, according to Ryan.

Closer Glen Perkins was the anchor of the bullpen, with a 2.30 ERA and 77 strikeouts in 62 2/3 innings. He also saved 36 games and was named an All-Star for the first time in his career.

The Twins also had two setup relievers they could count on in Jared Burton (3.82 ERA with 61 strikeouts in 66 innings) and Casey Fien (3.92 ERA with 73 strikeouts in 62 innings). Both went through inconsistent stretches during the season but were mostly solid, as Burton finished with 27 holds and Fien had 17.

Swarzak was a key piece as a long reliever, posting a 2.91 ERA with 69 strikeouts in 96 innings, which led all Major League relievers. And Duensing was the club's lone left-handed option outside of Perkins to open the season, and fared well with a 3.98 ERA with 56 strikeouts in 61 innings.

Given that both Swarzak and Duensing have starting-pitching experience, the Twins still haven't ruled out moving either one of them to the rotation next season.

Duensing has shuffled back and forth between starting and relieving the last few seasons, and even though it looked like he settled in to becoming a full-time reliever, the Twins are still open to him starting again.

"I still think there's a ceiling there we would like to see him get to," Twins manager Ron Gardenhire said about Duensing late in the season. "There's still talk about whether he should be a starter. I think this guy's got good stuff. Sometimes it doesn't play out on the field as much as we'd like it to. He doesn't get lefties out like we think he can. But I still think he can get better."

The Twins also saw a breakthrough performances from rookies Ryan Pressly (3.87 ERA with 49 strikeouts in 76 2/3 innings) and Caleb Thielbar (1.76 ERA with 39 strikeouts in 46 innings). Fellow rookie Michael Tonkin also showed promise in his first taste of the Majors with a 0.79 ERA with 10 strikeouts in 11 1/3 innings.

Pressly is also no longer bound to the rules of being a Rule 5 Draft pick, and can be optioned freely between Triple-A Rochester and the Twins next season. But given his success as a rookie, he figures to be part of the bullpen again next season along with Thielbar and likely Tonkin.

So given the number of quality arms the Twins have in their bullpen, the club can continue to primarily focus on adding starting pitching, which will only help the relievers by reducing the workload.

"We couldn't get the quality starts, so we need to start with the starting pitching and go from there," Ryan said. "Starting pitching was a problem. … Consequently we are going to have to go out and look, take every avenue possible to supplement this roster."