If you were trying to come up with ways to talk yourself into still attending some Mets games this last month of the season, you might have said, “Well, Johan Santana still pitches every fifth day, and he’s one of the best pitchers in baseball!!” As of this second, neither of those may be true. Santana left his start last night after five innings with an injury no one has quite deciphered just yet. It appeared to be his pectoral muscle, but someone said something about a biceps, and everyone’s all freaked out because he just had elbow surgery a month year ago. The Mets flew to Chicago for a series at Wrigley after the game — a game they won, by the way — and Santana went with them, so at least his arm is attached and the airport-security device that detects “career-ending arm injuries” didn’t flag him and not let him through. Whew. The Mets play at Wrigley in a couple of hours, and you really should leave work and watch. They’re only there once a year, and Wrigley is freaking gorgeous.