Musick was the Rockies' ninth-round pick in the 2009 Draft out of the University of Houston, following an up-and-down college career that included a torn ACL in his right knee and an elbow that required Tommy John surgery. Since those injuries, early on, he's been healthy and he spent his first full season in the Rockies' system pitching in the hitting-friendly confines of Asheville's McCormick Field.
Overall, the left-hander finished with an 8-7 record and a 4.05 ERA, walking 26 and striking out 109 in 122 1/3 innings. He started out very slowly, with a 5.08 ERA in the first half, but came on strong in the second, finishing with a 2.78 ERA in his final 10 starts. He clearly didn't enjoy pitching at home, where he had a 5.61 ERA and a .303 batting average against. But on the road, he was a different pitcher, with a 2.03 ERA and a .207 batting average against. For the year, lefties hit just .198 on the year (.283 vs. right-handed hitters), so the Astros at the very least could have a lefty situational reliever on their hands.
Musick will be 24 for the 2011 season, and he's a southpaw with a reputation as a strike-thrower. He throws his fastball in the 88-90-mph range with a good curveball. He does have the ability to get hitters to swing and miss. Whether he's able to remain a starter will depend on his ability to develop his changeup, something the Rockies had him working on this past year.
Aristil, 24 years old, had been with the Rockies since signing in July 2003. When he first came aboard, he was an infielder. He made the conversion to the mound in '06, making 13 appearances for the Dominican Summer League Rockies club. He made two short-season stops in 2007 and '08 before making his full-season debut in '09. In Asheville that season, he went 4-9 with a 5.06 ERA, largely as a starter, striking out 102 in 112 innings. Like with Musick this past season, Aristil was better on the road than in Asheville's band box (4.56 ERA vs. 5.49 ERA; .229 batting average against vs. .327 batting average against).
This past year, Aristil was almost exclusively a reliever, starting with Modesto in the California League, moving up to Double-A Tulsa and even getting a game in Triple-A Colorado Springs. He pitched well in relief with Tulsa, posting a 1.84 ERA in eight outings. He's pitched fairly well in the Dominican this winter, with a 3.72 ERA in nine relief outings.
With a 90-mph fastball and decent secondary stuff, Aristil profiles as a long reliever or a spot starter. He's willing to soak up innings and he's not afraid to take the ball in any situation.