Mets ace Johan Santana will miss the entire 2013 season after it was revealed that he tore the anterior capsule in his left shoulder for the second time in his career, an injury that will require surgery.

Details are scarce as to when or how the injury occurred, according to Mets general manager Sandy Alderson.

"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."

In 2010, Santana suffered the same injury and was operated on in September. He missed all of the 2011 season before returning to the Mets last April. Last season, Santana threw the first no-hitter in Mets history. In that game Santana hurled a career-high 134 pitches but was ineffective for most of his starts the rest of the way. He made 21 starts in total in 2012, and went 6-9 while posting a 4.85 ERA and 1.33 WHIP.

The Mets traded for Santana in 2008 and signed him to a six-year, $137.5 million deal. From 2008-2010, Santana lived up to the ace billing he attained while pitching for the Minnesota Twins, where his changeup gained a reputation for being one of the best pitches in baseball. Santana has been selected to four All-Star games and has won two Cy Young awards, in 2004 and 2006.

Now at 34 years old, Santana will face another grueling rehab period with the best-case scenario being a return in 2014. Alderson was not exuding optimism in a conference call when he outlined the prospects of a Santana return to CitiField, according to The Washington Post.

"I am not a doctor, nor am I a medical historian, but these injuries are very difficult to recover from after one surgery, and I'm not sure what the history is of recovery from a second more or less identical surgery," he said.

Peter Greenburg, Santana's agent, said that the ace didn't have any comment yet on the injury.

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