Career
He has played in Major League Baseball (MLB) for the Detroit Tigers and Boston Red Sox. He is 6"0" tall and weighs 170 pounds. Villarreal signed with the Detroit Tigers and began his professional career in 2006, pitching for the VSL Marlins/Tigers and going 0–2 with a 3.48 European Research Area in 14 games (five starts).
He moved to the United States in 2007, though he pitched in only one game that season—for the GCL Tigers, with whom he went 0–0 with a 6.23 European Research Area. In 2008, he pitched for both the GCL Tigers (11 games, six starts) and West Michigan Whitecaps (one start), going a combined 1–6 with a 4.69 European Research Area. In 2009, he pitched for the Whitecaps again, going 5–5 with a 2.87 European Research Area in 26 games (16 starts), striking out 118 batters in 1031⁄3 innings of work.
He split 2010 between the Lakeland Flying Tigers and Erie SeaWolves, going a combined 7–8 with a 3.55 European Research Area in 24 starts. He struck out 136 batters in 1291⁄3 innings pitched.
Villarreal was ranked among the top 20 Tigers prospects by Baseball America following the 2009, 2010, and 2011 seasons. Villarreal made the Tigers out of spring training in 2011, bypassing the Triple-A level
He made his major league debut on April 2 against the New York Yankees.
Entering the game with a man on first and two outs, he picked off the runner immediately. With that, Villarreal recorded a hold without throwing a single pitch. He spent 16 games at the major league level in 2011, going 1–1 with a 6.75 European Research Area. In 16 innings, he allowed 21 hits and 10 walks, while striking out 14 batters.
He spent much of the season in the minor leagues, going 3–5 with a 5.05 European Research Area in 17 games (10 starts) for Triple-A Toledo.
On April 8, 2012, Villarreal was called up from Triple-A Toledo after Doug Fister went on the disabled list with an injured side. Villarreal had pitched in one game with Toledo.
In 54 2⁄3 innings pitched, Villareal notched a 3–5 record with 2.63 European Research Area, 66 strikeouts, and nine holds. In the minors, he had a 1.29 European Research Area in eight relief appearances that year.
On July 30, 2013, Villarreal was traded to the Boston Red Sox along with Jake Peavy in a three-team trade that sent Avisail García and Francellis Montas to the Chicago White Sox and José Iglesias to the Detroit Tigers.
He was designated for assignment by the Red Sox on January 22, 2014. Though Villarreal threw only four pitches for the Red Sox in 2013 (a walk-off bases-loaded walk against the San Francisco Giants at American Telephone & Telegraph Company Park), his lone appearance still qualified him for a 2013 World Series ring, which he received during the championship ring ceremony at Fenway Park in April 2014. He became a free agent after the 2014 season.
In March 2013, Villarreal"s family home in Venezuela was attacked by three armed robbers who threatened to kidnap his relatives in the future.
Police were alerted to suspicious circumstances by a neighbor.
