The Rockies have summoned right-handed prospect Jhoulys Chacin and veteran righty reliever Juan Rincon from Triple-A Colorado Springs.
Since righty starter Jason Hammel (0-2, 9.16 ERA in four starts) also is headed to the disabled list with a right groin strain that he suffered Monday night in a 5-3 loss to the D-backs, the Rockies are planning to call up right-hander Esmil Rogers from Colorado Springs.
The De La Rosa injury costs the Rockies their second-best rotation member during the early portion of the season.
De La Rosa's 26 strikeouts were one better than ace Ubaldo Jimenez's 25. At the start of the year, De La Rosa was named the fourth starter, but with that came the honor of pitching the home opener, in which he threw seven innings of a 7-0 victory over the Padres.
The injuries to De La Rosa and Hammel come at a key time for the club. Monday's loss began 12 straight games within the National League West.
"I don't think anybody's going to feel sorry for us, that's for sure, and we're not going to sit around and feel sorry for ourselves," Tracy said. "In the face of adversity, opportunity presents itself."
Chacin, 22, is 3-0 with a 1.69 ERA in four starts at Colorado Springs, and has 21 strikeouts and 11 walks in 21 1/3 innings.
Rincon, 31, is 0-1 with a 4.91 ERA in eight games, and has seven strikeouts and seven walks in 7 1/3 innings of relief.
Rogers, 24, began the season on the Major League squad as a long reliever and posted a 2.25 ERA in three appearances, covering four innings, before being sent down on April 16, when the club activated veteran left-hander Joe Beimel. Rogers has an 0.90 ERA in two starts, with seven strikeouts and one walk in 10 innings at Colorado Springs.
Chacin ranked 44th on MLB.com's list of baseball's top 50 prospects this winter. Coming out of Spring Training, the Rockies felt he needed to improve his fastball command and use that pitch with greater regularity than he has. Chacin has bordered on dominant since beginning the year as the Sky Sox's ace.
Rogers struggled with mound presence early in spring, but clicked after being sent to Minor League camp. The decision to have Beimel, who signed in late March, open the year in the Minors, opened the way for the Rockies to name Rogers to the roster in a surprise. His early stint in the Majors and what he has done since being sent down confirmed the Rockies' hope that he would develop rapidly.