The 23-year-old Castro spent the majority of this past season in the Minor Leagues, posting an 8-4 record with a 4.71 ERA between stints with Triple-A Lehigh Valley and Double-A Reading in the Phillies' system. In 10 games with Philadelphia this year, Castro logged a 6.00 ERA over 12 innings.
At Double-A, Castro, a native of Montecristy, Dominican Republic, went 8-2 with a 4.40 ERA in 27 games, including 16 starts. The southpaw went 0-2 with an 8.10 ERA in three games at Triple-A. In 30 career Major League games, Castro is 0-2 with a 3.30 ERA and a .181 opponents' batting average between stints with Texas and Philadelphia.
Stairs, 40, hit .250 with 11 home runs and 44 RBIs in 105 games this season for the Blue Jays, who signed the Canadian to a two-year contract last offseason. Philadelphia agreed to pick up the remainder of Stairs' $2.25 million salary for the 2008 season, as well as the $1 million he's owed in '09.
Jordan Bastian is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.