The Chicago Cubs have traded Welington Castillo to the Seattle Mariners in exchange for reliever Yoervis Medina.
Castillo, 28, has played his entire six-year career for Chicago after the catcher was signed as an amateur free agent in 2004.
Medina, 26, who had a 3.00 ERA and one save in 12 games for the Mariners this season, will report to Triple-A Iowa.