Michael Pineda, the All-Star pitcher the Mariners traded to the Yankees in January, will have season-ending surgery on his right shoulder, according to reports.The controversial trade was one of the biggest of the offseason. M’s fans were understandably wary when GM Jack Zduriencik sent Pineda and minor-league pitcher Jose Campos to New York in return for rookie slugging prospect Jesus Montero and pitcher Hector Noesi.With a 3.74 ERA and 173 strikeouts last season, Pineda was becoming one of the most promising and exciting players on a struggling Mariners team. After five years in the minors, Seattle leaned on him last season when he was just 22 years old. As a rookie, Pineda was just one of three M’s on the 2011 A.L. All-Star team (with Felix Hernandez and Brandon League), and was fifth voting for A.L. Rookie of the Year.In Montero, the Mariners got one of the Yankees’ most promising hitting prospects, though there were concerns about his abilities as catcher. During spring training, Noesi swooped in and earned a spot on the Mariners’ starting rotation — though he has struggled during the beginning of this young season, giving up 13 runs for a 9.49 ERA in his first three starts.While the truth won’t be known for years (in theory), it’s beginning to look like the Mariners may have already won that trade — at least in the short term. The Yankees had been hoping Pineda would become a strong force in their starting rotation; instead, they lost Montero and will have to wait until next season, or longer, for production from Pineda.Pineda, 23, will have surgery May 1 to repair an anterior labral tear in his right shoulder. Yankees doctor Chris Ahmed said the surgery should take about 12 months of recovery time, CBS Sports reports, but he is optimistic about PIneda’s long-term health because his rotator cuff is not injured.“In no way do I believe the Seattle Mariners had any knowledge (of the injury),” Yankees GM Brian Cashman said in a conference call Wednesday, according to reports. “He was a fully healthy player when we acquired him. … This is just an unfortunate circumstance.”Here’s some more info from The New York Times about Pineda’s status during the past month:Pineda first reported pain in his right shoulder after a spring training start on March 30. He had a magnetic resonance imaging test the next day, which revealed tendinitis.Last Saturday, in his first stint on the mound since March 30, Pineda was shut down with more pain after throwing only 15 pitches in an extended spring training game.I must admit, I feel somewhat vindicated after so many readers flipped out when I asked, in March, whether the Mariners had already won the Pineda-Montero trade. To me, that was writing on the wall about Pineda’s long-term health, and suggested the Yankees may have gotten the short end of the stick.Which should please most Mariners fans, who have a longstanding hatred of the New York Yankees.But it’s sad news for Pineda, whom the Mariners developed from age 17 until his first major-league appearance in April 2011. For the first half of last season, Pineda appeared on track to become another pitching ace alongside fan-favorite Hernandez.But Pineda’s performance dropped off after the All-Star break. In his first 17 games last season, Pineda held an ERA well below 3.00; beginning with his July 9 start, his ERA sliped into the mid- and upper-3.00s, and his velocity declined noticeably. This spring, he showed up to Yankees training camp 10 pounds heavier and his velocity still lagged.“He didn’t have his velocity from Day 1, and we didn’t know why,” Cashman said. “This must have been responsible. Clearly, he was fighting through something.”According to ESPN, Cashman made sure Wednesday to not blame the Mariners:“In no way do I believe, or do the New York Yankees believe, that the Seattle Mariners had any knowledge of any issues here with Michael Pineda prior to the trade or anything of that nature,” he said. “He was a fully healthy player we acquired. We had full access to his medicals, which were clean. We had the opportunity to do a full physical exam, which we did, which came out clean. Michael has never had a shoulder issue nor has he complained of one with the Mariners, nor has he ever had any tests on the shoulder with the Mariners.“This is just an unfortunate circumstance that can happen. It happened. Regardless of what happened, and I know he hasn’t thrown a pitch for us, it’s just timing is unfortunate. The Mariners obviously, there’s nothing there. No further questions to pursue on that issue. Jack and the Mariners, we got a healthy player to the best of everyone’s knowledge as they conducted themselves.”Visit seattlepi.com for more Seattle news. Contact Nick Eaton at or on Twitter as @njeaton.