The Rockies attempted to acquire Lindstrom in November when they obtained righty Felipe Paulino from the Astros for infielder Clint Barmes, but the clubs could not find a match. Lindstrom, 30, was 2-5 with a 4.39 ERA for the Astros last season. He is arbitration-eligible, and there were reports that Houston wanted to move him to keep the payroll manageable.
"We were very reluctant to trade Matt," said Astros general manager Ed Wade. "But with Brandon Lyon, Wilton Lopez and some of our younger arms, we think we have good coverage at the back of the bullpen. Matt is a great guy and a great competitor and we wish him well. We've added two young arms to our prospect depth and we think both [Jonnathan] Aristil and Musick have a chance to help us down the road."
Musick, who turns 24 on Dec. 30, was the Rockies' ninth-round pick in the 2009 First-Year Player Draft and went 8-7 with a 4.05 ERA in 23 starts and 122 1/3 innings at Class A Asheville. It was his first full Minor League season. Musick struck out 109 and walked 26.
A native of Lufkin, Texas, Musick actually was drafted out of high school by the Astros in the 46th round of the 2005 Draft.
At the University of Houston, he ranked among the Conference USA leaders in wins, ERA, strikeouts, innings pitched and opposing average in his sophomore season in 2008. The lefty won his first five decisions to open the season.
The Astros also get the right-handed Aristil, 24, who played for the Rockies' Dominican Summer League team as an infielder from 2004-06 before converting to pitching. Last season, he went a combined 2-5 with a 5.90 ERA in 33 games (four starts) at three levels. He was 1-4 with a 7.12 ERA while appearing in relief for all but one of his 21 games at Class A Modesto, 1-1 with a 4.39 ERA with three starts in 11 appearances at Double-A Tulsa, and made a scoreless two-inning appearance for Triple-A Colorado Springs.
In eight appearances in the Dominican Winter League with Los Toros del Este, he is 1-0 with a 2.08 ERA and a .226 batting average against.
Lindstrom, who has an offseason home in the Denver area, has earned 43 career saves, including 23 for the Astros last season. He began the year as Houston's closer but was on the disabled list because of back issues. He joins Rafael Betancourt and Matt Belisle as the Rockies' primary right-handed setup men.
"It's pretty exciting," Lindstrom told MLB.com on Thursday. "It's a little bit bittersweet because I enjoyed my time in Houston so much, and all my teammates and everyone was really good to me down there. I'm going to miss even [the media]. At times I wasn't as good as I thought I was, but [the media] wasn't too hard on me. I'm really excited to get going to Colorado and help them out and provide late-inning relief, especially because that's where I spend my offseason."
Lindstrom said he had talked to both Wade and Rockies general manager Dan O'Dowd on Thursday.
"[O'Dowd] clued me in on what they're going to have me do and that's provide late-inning relief," he said. "Whatever the innings may be, there's a lot of good guys over there already and hopefully I can contribute."
Lindstrom will give Colorado protection in case Huston Street gets injured. Street missed the first 69 games last season with a shoulder injury and suffered some setbacks during his rehab.
"There were things I learned through my journey last year," Lindstrom said. "I'm just going to take care of myself and be healthy all year, and I know if I can do those things, good things will happen."
When asked how he feels now, Lindstrom said: "Feel awesome."
Carrie Muskat is a reporter for MLB.com. She writes a blog, Muskat Ramblings, and you can follow her on Twitter @CarrieMuskat. Brian McTaggart contributed to this report. This story was not subject to the approval of Major League Baseball or its clubs.