"We just don't know when this occurred," Alderson said. "We don't know when it happened, how it happened. But what we do know is that at some point, symptoms appeared, and they worsened rather than improved."
Battling what the Mets diagnosed as left shoulder weakness throughout this spring, Santana flew to New York this week for an MRI at the Hospital for Special Surgery in Manhattan. After team orthopedist Dr. David Altchek diagnosed a probable re-tear of Santana's shoulder capsule, the left-hander sought second opinions from renowned surgeons Dr. James Andrews and Dr. Lewis Yocum. That pair confirmed the diagnosis.
"I'm not a doctor or a medical historian, but these injuries are very difficult to recover from after one surgery," Alderson said. The GM was unwilling to speculate on Santana's chance to recover from a second, identical operation.
Santana, 34, missed the entire 2011 season following surgery to repair his torn left shoulder capsule in September 2010. He returned to the Majors 19 months later, going 3-2 with a 2.38 ERA from Opening Day 2012 through his June 1 no-hitter, the first, and only, in Mets history. But he was not the same pitcher after that, posting a 3-7 record and 8.27 ERA in his last 10 outings.
With Santana battling ankle, back and shoulder issues, the Mets finally shut him down in mid-August; he went 0-5 with a 15.63 ERA over his final five starts.
Santana reported to Spring Training in mid-February ostensibly healthy after a winter of rest, pitching a bullpen session within days of arriving at camp. But the Mets quickly diagnosed him with left shoulder weakness, and Alderson sparred publicly with the pitcher over his general conditioning. Santana had been limited to a long-toss regimen in recent weeks.
In one much-publicized early-March episode, Santana threw a surprise mound session the day after Alderson criticized his lack of preparedness for Spring Training. Manager Terry Collins and pitching coach Dan Warthen both speculated afterward that Santana did so solely to prove he was healthy.
Whether that contributed to his injury, however, is impossible to say.
"There was a belief on our part that his arm was fine," Alderson said.
With one guaranteed season remaining on his six-year, $137.5 million contract, Santana's time in New York is almost certainly finished, and his career could also be in jeopardy. Alderson said that the final year of Santana's contract is not insured, meaning the Mets will still pay him his full $25.5 million salary in 2013, as well as the $5.5 million buyout on the 2014 option year of his deal.
One of the most successful pitchers of his generation, Santana went 111-51 with a 2.88 ERA from 2003-09 with the Twins and Mets, winning the AL Cy Young Award in 2004 and 2006 while with Minnesota. He finished third in NL Cy Young Award voting in his first year in New York, pitching the penultimate game of the season with an injured right knee. Santana underwent knee surgery in 2008 and elbow surgery in 2009 before his shoulder operation in 2010.
Now that he appears headed for a second shoulder surgery, the Mets must decide who will replace him. The team had already been bracing to play most of the early season without Santana, naming Jon Niese its Opening Day starter and sliding Jeremy Hefner into the rotation. But with Shaun Marcum battling a neck injury and Jenrry Mejia shut down for two weeks due to elbow tendinitis, the Mets' depth chart is perilously thin.
"We are not terribly deep right now with Santana out indefinitely," Alderson said. "On the other hand, we do feel that we have some -- not just depth in the system, but also some exceptional talent coming through the system. We'll just have to see how our needs and the maturation of that talent connect."
The unspoken reference is to top prospect Zack Wheeler, one of the most talented pitchers in all of the Minors. The Mets have made it clear that they will not call up Wheeler until at least midseason, and Alderson reiterated that in light of Santana's injury.
"We will bring him up when he is ready," Alderson said. "No immediate need will impact that."