Brandon Lyon is likely to undergo season-ending surgery to fix a biceps tendon in his pitching arm. Lyon's tendon is "out of its groove" and is unlikely to improve with rest and rehabilitation, so surgery appears to be the only option. It's a rare procedure, as Dr. Lewis Yocum and Dr. David Lintner, who have both examined Lyon, couldn't think of one pitcher that has had the operation. For that reason, it's not clear how long Lyon might be sidelined, though he certainly would not return this season. Mark Melancon is likely to remain the Astros closer for the rest of the year.