On July 3, the versatile righthander threw for the first time since going on the disabled list in mid-May with a strained right elbow.
But during a recent throwing session, McClellan suffered a torn labrum, and Tuesday he underwent shoulder surgery in St. Louis. Team physician Dr. George Paletta performed the procedure.
McClellan, who originally had been tracking toward a mid-August return, will not pitch again in 2012.
McClellan, who had been moved back and forth between the Cardinals’ rotation and bullpen in 2011 (17 starts, 26 relief appearances), said the heavy workload could have contributed to him not feeling right all year, according to Strauss. He had a 5.30 ERA and 1.339 WHIP before hitting the disabled list two months ago.