The Mets placed Hefner on the disabled list Aug. 11 after learning he had a partially torn medial collateral ligament. A visit to a specialist resulted in a recommendation for Tommy John surgery. Hefner received a second opinion from Dr. James Andrews, who confirmed that prognosis.
The surgery will end his 2013 campaign and put Hefner's 2014 season in jeopardy. It typically takes a player about a year to recover from Tommy John surgery.
Hefner, 27, was in just his second major league season with the Mets in 2013. He had helped solidify New York's rotation with a 4.34 ERA and 1.29 WHIP over 24 appearances.
It's been a rough day for the Mets when getting news about starting pitchers. Earlier Monday, the team found out that youngster Matt Harvey has a partial tear of his UCL and will likely need Tommy John surgery. Harvey, 24, had been a Cy Young candidate this season.