Joe Nathan put everything he had into rehabilitation following Tommy John elbow ligament replacement surgery in March of 2010 to be ready for the start of the 2011 season. And he accomplished that.

Yet he hasn't been the pitcher he wants to be -- or the Twins need -- posting a 7.63 ERA with opponents batting .353 off him.

Now with his elbow hurting, Nathan is headed to the 15-day disabled list to work the inflammation out of the area and hopefully return a better pitcher.

"You never want to have a setback to put you on the DL," he said. "This is a situation where we want to take care of this thing and kind of gradually get better as the season goes on."

"And doing what I'm doing now, it's just kind of keeping on a level. It is not getting much better. We feel like we have a pretty good plan as far as treatment right now."

Nathan doesn't know when he will return to the mound. He is eligible to come off the disabled list June 8, but it depends on when the soreness subsides and he's able to get on a throwing program and work on his pitches.