Although the club's official announcement said the next step is being discussed, manager Jim Tracy said De La Rosa (5-2, 3.51 ERA) is headed for season-ending Tommy John surgery. No teammate gave any indication another route was feasible.
"It's a Tommy John surgery," Tracy said. "It's another card that comes your way, and you have to deal with it."
The work of De La Rosa, who was making himself a serious candidate for the National League All-Star team, is one of the reasons the Rockies are above .500 despite an inconsistent, mostly substandard, offense.
Not only that, but he was the only lefty on the starting staff. In addition, Matt Reynolds is the lone bullpen lefty, so the Rockies' staff is heavily right-handed. But Tracy said the Rockies have overcome injuries before and will do so again.
"The one thing I know about this club since I joined in 2009 is its resiliency," Tracy said. "We have to move on and find ways."
Tracy said the Rockies will discuss how to proceed and he would have that information Wednesday.
Early indications Tuesday were the Rockies were considering bringing up hard-throwing right-hander Juan Nicasio, 24, from Double-A Tulsa to pitch on the staff in some capacity. Nicasio is 5-1 with a 2.22 ERA in nine starts, with 63 strikeouts against 10 walks.
The club has five starters on hand. Right-hander Greg Reynolds, who was called up over the weekend from Triple-A Colorado Springs, entered when De La Rosa was removed in the third inning Tuesday and pitched 3 2/3 strong innings (one run, three hits, two strikeouts) for the decision in the 12-4 victory over the D-backs. Reynolds will start Saturday against the Cardinals.
If a starter-type such as Nicasio is called up, it could be for protection -- much the same role that Reynolds filled Tuesday. The starting staff is expected to receive another boost soon. Veteran right-hander Aaron Cook, who hasn't pitched this season because of a fractured right ring finger, will make his final injury rehab start at Triple-A Colorado Springs on Saturday and should return to the rotation shortly thereafter.
Righty Esmil Rogers (3-1, 7.66 ERA) also is on the disabled list with a right lat strain and has yet to begin a rehab assignment. But Rogers threw a bullpen session on Tuesday, and said he hopes to soon move into simulated games -- the step before a rehab assignment.
Reynolds said he is ready, as he was Tuesday, to help in any capacity.
"He's a big part of our team -- not too many guys have stuff like Jorge," Reynolds said. "Someone's going to have to step up. If that's me, I'll be ready for the challenge. If they go another route, I'll do whatever they want me to do."
De La Rosa is 39-26 in 85 starts since joining the Rockies in 2008, after time with four organizations that had been marked by inconsistency. This past offseason, De La Rosa and the Rockies reached a two-year, $21.5 million contract with a player option for 2013 valued at $11 million and a club option for 2014, also worth $11 million.
With ace Ubaldo Jimenez having battled a thumb injury and currently winless, De La Rosa emerged as a veteran staff leader. De La Rosa went 4-0 in five April starts, despite working around a blister issue with his left middle finger. He has gone 1-2 in May, but one of the losses was his first career complete game, when he gave up two runs -- one earned -- in a 2-1 loss to the Phillies last Wednesday.
"Throughout the course of the season, guys are going to get hurt -- key guys," veteran first baseman Todd Helton said. "You've got to find ways to overcome that. Obviously, he's our best starting pitcher. To lose him for the season and part of next is a blow, but it's something we have no choice but to overcome."
On Tuesday, De La Rosa lacked velocity and gave up three hits and two walks early, although he struck out three.
Asked if he sensed something was wrong, catcher Chris Iannetta said, "In hindsight, I did. While it was going on, I thought it was a day when he didn't feel that great."
After throwing a pitch to Chris Young with runners at second and third, De La Rosa, encouraged by Iannetta, motioned to the dugout for head athletic trainer Keith Dugger and Tracy. De La Rosa threw a warmup pitch, which is normally allotted to an injured pitcher.
"All I had to see was the expression on his face when he turned the ball loose, and I said, 'That's all,'" Tracy said.
Thomas Harding is a reporter for MLB.com. Read his blog, Hardball in the Rockies, and follow him on Twitter @harding_at_mlb This story was not subject to the approval of Major League Baseball or its clubs.