Pena came to the Brewers from the Angels in July 2012 along with Johnny Hellweg and Jean Segura for Greinke. Hellweg underwent Tommy John surgery and was let walk in Minor League free agency following last season, and Segura was traded to the D-backs in January for three players. Pena made Milwaukee's Opening Day roster in part because he was out of options, and he surrendered back-to-back-to-back home runs in the eighth inning of Monday's Opening Day loss to the Giants.
Freeman, 28, has a 3.23 ERA in 135 appearances over the past four seasons for the Cardinals and Rangers. Like Capuano, Freeman is not a lefty specialist; he has actually been tougher on right-handed hitters in his career, holding them to a .513 OPS. Left-handed hitters have an .816 OPS against Freeman.
The Rangers designated Freeman for assignment last week after trading for catcher Bryan Holaday.
Adam McCalvy is a reporter for MLB.com. Follow him on Twitter @AdamMcCalvy, like him on Facebook and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.