De La Rosa was placed on the DL May 25, one day after leaving in the third inning of a 5-2 loss to Arizona with elbow soreness. De La Rosa was later taken to a hospital an had an MRI which revealed a complete tear of the ulnar collateral ligament in his left elbow.
De La Rosa was the Rockies' top pitcher this season with a 5-2 record and a 3.51 ERA. He was coming off his first career complete game when he got hurt.
Colorado got some encouraging news on two of its other pitchers.
Right-hander Aaron Cook, out since March 31 with a fractured right index finger, is penciled in to start for the Rockies against San Diego on Wednesday. Another righty, Esmil Rogers, threw 67 pitches in extended spring training and the team is discussing where to send him next in his recovery from a strained lat muscle in his right shoulder.