The only 2010 Minnesota starter with more than five starts and an ERA under 4.50 this season is Scott Baker, who has compiled an ERA of 3.21. Baker is also the only Twins starter with a winning record.
Gardenhire said two current starters, Brian Duensing and Nick Blackburn, could transition well to the bullpen if the Twins make changes to their starting rotation.
"Duensing's got enough ability to go to the bullpen and make our bullpen better. Blacky could do it with that sinker ball," said Gardenhire.
Two in-house options for the Twins to fill rotation spots next year are Anthony Swarzak and, to a lesser extent, Twins top pitching prospect Kyle Gibson. Earlier this month, Gibson was sent to Fort Myers, Fla., to rehab a partial ligament tear in his right elbow.
If Gibson could've avoided injury, there was a good chance he would've made his Major League debut this season, but now he could be facing Tommy John surgery if his elbow does not respond to rehab.
"We had a guy who got hurt who I think we were definitely going to get a look at, but that's not going to be an option," Gardenhire said.
Swarzak has been a reliable spot starter and long-relief option for the Twins this season, which has opened his manager's eyes.
"I like Swarzak. I like the way he throws the ball. He's been very valuable," said Gardenhire. "I am not afraid to give him starts. He is another guy who will be in that mix in Spring Training."
Swarzak has compiled a 3-3 record with an ERA of 3.25 and has made five starts this season.
Other options for next year's rotation could come in trades or through free-agent signings, but that will be left up to general manager Bill Smith.
"It depends on what [the front office does] over the winter. That will tell me what I am going to do with my rotation," Gardenhire said.