Parra was moved to the bullpen in 2010. On June 6 of that year, Parra became the 52nd major league pitcher to strike out four batters in an inning, doing so against the St. Louis Cardinals. Problems with his back and the necessary surgical removal of a bone spur in his throwing elbow resulting in him missing the entire 2011 season. He continued in a relief role for the Brewers in 2012, but was released at the season's end. After five years with Milwaukee, Parra held a 26–33 record with a 5.12 ERA in 74 starts and 98 relief appearances.