The 26-year-old Carrillo was the Padres' first-round pick, 18th overall, in the 2005 First-Year Player Draft and made three starts for San Diego in 2009, going 1-2 with a 13.06 ERA in three starts. This season, he was 5-14 with a 5.60 ERA in 27 starts at Triple-A Portland.
However, he has been designated for assignment twice this month. The Padres designated him Sept. 1, and Carrillo was claimed off waivers by Philadelphia on Sept. 9. The Phillies waived him and San Diego reclaimed the right-hander on Sept. 15 before designating him for assignment on Sept. 20.
Carrillo will not see time with the Astros this season.
Maysonet hit .276 with a homer and seven RBIs in 46 games for Houston from 2008-09, but played exclusively in the Minors in 2010, batting .248 with two homers and 40 RBIs in 90 games for Triple-A Round Rock and the Rookie League Gulf Coast Astros.