ARLINGTON, Texas -- When Michael Pineda went on the disabled list March 31 with tendinitis in his pitching shoulder, general manager Brian Cashman breathed a sigh of relief. The "worst-case" scenarios, he said, had been eliminated.
Cashman and the Yankees were not so fortunate Wednesday.
The jewel of Cashman's offseason -- acquired in the deal that sent top prospect Jesus Montero to the Mariners -- will be sidelined for at least a full calendar year after being diagnosed with an anterior labral tear in his right shoulder.
Pineda will have arthroscopic surgery next Tuesday, performed by Dr. David Altchek of the Hospital for Special Surgery -- he's also Mets medical director -- and assisted by Yankees physician Christopher Ahmad.
The diagnosis came after Pineda, 23, had a dye-contrast MRI Tuesday, determined to be necessary after he left an extended spring training start Saturday after 15 pitches.
"Obviously, this was a big move I pursued this winter," Cashman said on a conference call before Wednesday night's's game. "You always go in with eyes wide open that there's risk associated with pitching, but to experience this on the front end, it's extremely difficult. But it's even more difficult for the player."
The 6-7 Pineda showed up for spring training overweight, and although he shed 10 to 15 pounds, his 95- to 97-mph fastball from last season never materialized. After leaving a start March 31 against the Phillies, he complained of shoulder soreness and admitted overthrowing to try to generate velocity. An initial MRI showed right rotator cuff tendinitis, and he had no setbacks in his throwing program until Saturday.
"The belief is that, without a doubt, that injury occurred during [Saturday's] rehab outing," Cashman said. "But I think it's real fair to speculate there was maybe something there laying dormant that wasn't detectable via the regular MRI. The dye-contrast MRI revealed something very significant."
Cashman insisted, as he did when Pineda went on the DL, that the Yankees do not believe they received damaged goods from the Mariners. "He was a fully healthy player that we acquired," he said. "We had full access to his medicals, which were clean."
Dr. Ahmad, also on the conference call, said there was a bit of a silver lining because the dye-contrast MRI didn't show damage to the rotator cuff.
"We're being cautiously optimistic," Ahmad said. "His rotator cuff looks very, very good. When the rotator cuff is damaged as part of the injury, that has a much worse prognosis and influence [on] his velocity and ability to pitch. This is isolated to his labrum, and that's why we feel a little bit more optimistic about him having a good result."
But Cashman nonetheless called the injury "significant" several times and once described the diagnosis as "tragic."
During spring training, Cashman tamped down expectations for Pineda, saying the Yankees didn't think they'd acquired a ready-made No. 2 starter, but expectations were for him to settle in the back end of the rotation and make about 30 starts.
"It's a loss," Joe Girardi said Wednesday. "He was a guy we were counting on for this year when we traded for him."
Pineda was 9-10 with a 3.74 ERA as a rookie last year and made the AL All-Star team.
Said Cashman: "Bottom line is you feel terrible about the situation Michael's facing right now. Hopefully, all this will do is delay an eventual performance that Yankee fans can be proud of in the future. But we will not see any benefit from Michael in the year 2012."
How much, and in what form, in 2013 becomes the next big question.