The 26-year-old Medina provides the Cubs experienced bullpen depth and has been used as a set-up man in Seattle the past two years, going 4-6 with a 2.91 ERA in his debut season (63 games) and was 5-3 with 2.68 ERA in 66 games last year. He appeared in 12 games for the M’s this season before being sent to AAA Tacoma. He throws a fastball in the mid-90s with a sinker and curve, and has a career BB/9 of 4.9 during his big league career. The Venezuelan native signed with the Mariners back in 2005 and has spent 10 years in the Mariners organization. Medina will be added to the Cubs 40-man roster and will report to AAA Iowa.
Castillo was signed as a non-drafted free agent in December of 2004 and had the longest tenure of any Cub player in the organization. He began his career in the Dominican Summer League and moved his way up the Cubs system playing in Mesa, Boise, Peoria, Daytona, Tennessee and Iowa before making his Cubs debut on Aug. 11 in San Francisco in 2010. In six big league seasons he hit .252/.319/.396 with 29 HR and 10 RBI in 311 games. Castillo became expendable after the trade for Miguel Montero and the signing of free agent David Ross.