Mets pitcher John Maine underwent season-ending arthroscopic surgery on his troublesome right shoulder Friday. Maine is making $3.3 million this season and is arbitration-eligible, meaning the organization is near-certain to cut him loose by the non-tender deadline in December. He was a 15-game winner in 2007, but his velocity did not return after he had surgery in September 2008 to remove a bony growth from his right shoulder socket.