Marcum, 31, had surgery in July for thoracic outlet syndrome. TOS results from extra pressure in the neck and rib muscles due to compression, causing nerve damage. With Marcum, he felt numb and cold in his pitching hand. Because of that, he could not properly grip a baseball and thus could not pitch.
Rex Gary, Marcum's agent, says that Marcum is progressing well and will be on a normal offseason routine in the next few months. Marcum made just 21 starts in 2012 with the Brewers due to an elbow injury, resulting in him accepting a one-year deal with the New York Mets for 2013.
In New York, Marcum pitched in 14 games, two of which he came on in relief. Over 78⅓ innings, he posted a 5.29 ERA and 1.35 WHIP. Before undergoing surgery, he had been under constant threat of being removed from the team's rotation and did not start for two weeks at the beginning of June.