Speier is on the disabled list with a strained left hamstring. The injury has healed, but the Rockies want Speier to correct issues with his delivery that cropped up when he was trying to compensate for the hamstring.
Since starting his rehab assignment, Speier has made six appearances -- three apiece at Class A Modesto and Double-A Tulsa -- and has a 3.00 ERA. He has joined Triple-A Colorado Springs and could pitch an inning Tuesday night.
"We're really trying to refine him -- not redefine him -- and get him locked into an arm slot, parallel to the ground," Rockies manager Clint Hurdle said. "It's been much better lately, the consistency of it, than it was earlier.
"As we'd anticipated, when he had some people on base, his mind-set was he'd go back to getting his arm up, go back to where he was when he left. We're really just getting him to maintain his arm slot and pitch with his arm on top of the ball."
Hurdle said he'd like to see Speier have "a couple, three outings," and was open to the possibility of testing him in back-to-back games before activating him.
Speier and right-handed setup man Taylor Buchholz were considered cogs in the late relief operation going into the season. Speier, whose effectiveness was reduced by the leg pain, had a 4.76 ERA in five appearances before going on the DL. Buchholz suffered an elbow ligament strain in Spring Training.
In other injury news:
Left-hander Franklin Morales threw a 60-pitch simulated game on Tuesday. The session went much better than an earlier one in Atlanta, when the teammates who were in the batter's box were at risk.
"I threw a lot of strikes today," Morales said.
Hurdle said the Rockies will discuss where they'll send Morales on his injury rehab assignment.
Buchholz will throw a bullpen session on Wednesday and pitch a simulated game on Saturday.
Left-hander Greg Smith, who came over from the Athletics in the Matt Holliday trade but hasn't thrown a pitch for the Rockies because of a shoulder strain suffered in Spring Training, left his start Sunday for Triple-A Colorado Springs with a blister and an "achy arm." As of now, however, he's still scheduled to start for the Sky Sox on Friday. The Rockies will monitor the situation.
Thomas Harding is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.