Baker was originally scheduled to have season-ending surgery to clean up scar tissue on his flexor pronator tendon on Tuesday, but Dr. David Altchek decided that Baker also needed to have his ulnar collateral ligament repaired.
"It happens more often than you think, when someone has something and you go in and all the sudden it's a little different than you expected," Twins general manager Terry Ryan said. "And that is the case here."
Ryan said the recovery time will be 12-plus months, so there remains a possibility Baker won't be ready in time for the start of the 2013 season. Baker was originally scheduled to need six months of rehab before the decision was made to repair his UCL.
Ryan said that the two MRI exams taken on Baker leading up to the surgery didn't show a torn UCL, but that there was a possibility he would need the operation after examining the ligament following cleaning out the scar tissue in the tendon.
Baker, though, caused confusion during his news conference at Target Field last Wednesday, as he told reporters that the ligament looked great. But Ryan said there was a reason why the surgery wasn't simply arthroscopic.
"I do remember that, and I was a little less optimistic," Ryan said about Baker's comments. "When you don't scope something that means they're concerned, and they didn't scope it. That's why they went in, just in case they needed to repair it -- and that's what happened."
There's no guarantee Baker will be back with the Twins, as the club holds a $9.25 million option for next year. It's unlikely the Twins will exercise the option, but there's a chance the club could re-sign him at a discounted price.