Parra attended spring training with the Brewers in 2007 where he allowed no runs or hits while striking out 3 batters in 3+1⁄3 innings over 4 relief appearances.[2] He was assigned to Double-A Huntsville to begin the 2007 season. After 13 starts, he had a win–loss record of 7–3 with a Southern League-leading 2.68 ERA.[4][6] He was promoted to the Triple-ANashville Sounds in mid-June to replace ace pitcher Yovani Gallardo who had been called up to Milwaukee.[4] Parra made his first career Triple-A start on June 20—a 3–0 loss in which he allowed 2 runs on 7 hits and 4 walks while striking out 6 batters in 6 innings.[6]
On June 25, 2007, Parra's second Triple-A start, he pitched a perfect game against the Round Rock Express.[8][9] This was only the third nine-inning perfect game in Pacific Coast League history.[9] In all, Parra stuck out 11 batters, achieving strikeouts in every inning except the eighth.[10] Six ground outs and 10 fly outs accounted for Parra's other outs in the game.[10] Seventy-seven of his 107 pitches were counted as strikes.[10]
After just two more Triple-A starts, Parra made his major league debut on July 20 against the San Francisco Giants.[3] Coming on in relief, he surrendered no runs over 1+1⁄3 innings and struck out 3 of the 4 batters he faced.[11] Parra appeared in eight more games, including two starts,[3] before breaking his left thumb during a bunt attempt in a game on August 30,[12] which forced him to finish the season on the disabled list.[4] Parra ended the campaign with an 0–1 record and a 3.76 ERA in 9 games with the Brewers.[3]
He returned to the mound at the beginning of the 2008 season, in which he had a 10–8 record.[3] Despite throwing 17 wild pitches in that season, tying for the major league lead,[13] his split-finger fastball was the most effective among major league starting pitchers.[14] He remained in Milwaukee's starting rotation through 2009.[3]
Parra was moved to the bullpen in 2010.[3] 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.[15] 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.[16] He continued in a relief role for the Brewers in 2012, but was non-tendered at the season's end and became a free agent. After five years with Milwaukee, Parra held a 26–33 record with a 5.12 ERA in 74 starts and 98 relief appearances.[3]
Cincinnati Reds
On February 1, 2013, the Cincinnati Reds signed Parra to a one-year contract. He pitched in the bullpen with the Reds as a middle reliever. On April 26, he was placed on the disabled list with a strained pectoral muscle, and missed almost a month.[17] From June 11 to July 28, he had a 19-game, 15.1 inning scoreless streak. In a year where he filled in for the high expectations of Sean Marshall, he shined, going 2–3 with a 3.33 ERA and 16 holds, striking out 56 in 46 innings (57 games). He entered June with a 6.23 ERA, and starting on June 11 to the end of the season, he had a 1.78 ERA in 35.1 innings.
On November 27, 2013, Parra agreed to a two-year, $5.5 million contract with Cincinnati.[18] In 150 relief appearances from 2013 to 2015, Parra accumulated a 3–8 record with a 3.91 ERA before reaching free agency after the 2015 season.[3]
Chicago Cubs
In 2016, Parra signed a minor league contract with the Chicago Cubs that included incentives potentially bringing the total value of the deal to US$2.7 million if he made the 40-man roster.[19] Despite a strong showing in spring training, he was released by the Cubs and resigned to a new minor league contract on the same day in late March. Ultimately, Parra missed the entire 2016 season following Tommy John surgery in early April.[20] In 2017, he was signed to a minor league contract and pitched out of the bullpen on 11 occasions for Chicago's Triple-A Iowa Cubs.[5] He was released on June 25 with an ERA of 14.09.[6]
Though Parra was selected by the Long Island Ducks in the Bridgeport Bluefish dispersal draft,[21] he later signed a minor league deal with the San Francisco Giants in February 2018.[22] He pitched for their Triple-A Sacramento River Cats that season and was granted free agency after its end.[5]
On March 11, 2021, Parra was loaned to the Mariachis de Guadalajara of the Mexican League, a new expansion team.[24][25] In 8 relief appearances, Parra posted a 3.18 ERA and 5 strikeouts over 5.2 innings pitched.
Leones de Yucatán (second stint)
On July 19, 2021, Parra was returned to the Leones de Yucatán of the Mexican League.[26] He made 6 appearances for Yucatán, registering a 1–1 record and 3.27 ERA with 5 strikeouts in 11.0 innings pitched.
Parra retired from professional baseball in February 2022.[27]
