During early spring training in 2010, Guzmán suffered significant ligament tears in the front bottom of his right (throwing) shoulder. The injury was thought to be career-threatening. On March 18, after consulting with Dr. James Andrews, Guzman had surgery on his shoulder, and missed the entire season. After the season, the Cubs outrighted Guzmán from the 40 man roster and signed him to a minor league contract with an invitation to spring training. He returned in 2011 to make 17 starts for the A class Daytona Cubs.