PHOENIX -- When he learned that an MRI of his right elbow showed a tear in the ulnar collateral ligament, D-backs right-hander Taijuan Walker was surprised.
After being removed from his start against the Dodgers last Saturday with forearm tightness, Walker passed strength tests and did not feel like the injury was serious.
Wednesday, Dr. David Altchek confirmed the first opinion that Walker would need Tommy John surgery and be out at least for the next 12 months.
"It was very disappointing especially how I felt," Walker said. "It didn't feel that serious. It still doesn't, but the MRI showed a pretty big tear in there, and I think the best option is to get it done, get it fixed and rehab and be ready to come back next year."
D-backs manager Torey Lovullo also said he was surprised by the severity of the injury.

"It's a tough situation for all of us to walk through," Lovullo said. "I asked him to stick around. I asked him to be around because I want to make sure that we help him out through these tough days."
Dr. Altchek will perform the surgery next Wednesday in New York.
"It's going to be a long process," Walker said. "It's going to be a long journey, but I've got a really good support system here with the guys."
Matt Koch will start in Walker's place Friday against the Padres. It's possible the D-backs could shuffle starters in that fifth spot until deciding on a permanent solution. That's what they did last year, using Braden Shipley and Zack Godley before finally deciding on having Godley fill the role.