SAN FRANCISCO -- Rockies right-handed reliever Ryan Speier, who could be a huge help to the bullpen, is planning to throw a simulated game Monday in San Diego as he completes his return from a left hamstring strain.

Speier estimated he threw 50-60 pitches in a bullpen session Saturday. It rained during the Rockies' entire time in San Francisco, but Speier expects to take advantage of better weather in San Diego to continue his comeback. He isn't sure when he'll take the last big step to a return to the roster -- a Minor League rehab assignment -- but he hopes to do it soon.

The Rockies have not received consistent pitching late in games. The absences of Speier and right-hander Taylor Buchholz (strained elbow ligament) have not helped.

"It's pretty miserable sitting around watching," Speier said. "But it's better when the team is playing well, and we have been for the last five or six games. I want to come back and be a part of it."

Speier hasn't pitched since April 18. He was strong early in Spring Training, but the righty suffered the injury about 10 days before the regular season began. He pitched through the injury and had a 4.76 ERA in five appearances before the injury forced him out of uniform.

Speier said he is working on lowering his primary arm slot. He had to raise it because the injury didn't allow him to bend properly.