McClellan announced his retirement Thursday, Jenifer Langosch of MLB.com reports. The right-hander endured nearly a year-long rehabilitation process after undergoing shoulder surgery last November, but his doctor told him simply that he wouldn't be able to pitch at a high level ever again. McClellan posted a 3.79 ERA and 1.28 WHIP over 268 appearances (17 starts) at the major league level, the last of which came with the Rangers in 2013.