Draft and minor leagues The Indians selected Allen in the 23rd round of the
2011 MLB draft. Allen signed with Cleveland and spent 2011 with four teams in the Indians' farm system, but spent the majority of the season with the
Mahoning Valley Scrappers of the
Class A-Short Season New York-Penn League, pitching to a 3–1
win–loss record with a 2.14
earned run average (ERA) in 14 games. Between the four teams, he was 5–1 with a 1.65 ERA, and 75
strikeouts in 54.2
innings, averaging 12.3 strikeouts per 9 innings. The following year he spent most of the season with the
Columbus Clippers of the
Class AAA International League, going 3–2 with a 2.27 ERA in 24 games. Pitching for three minor league teams, he was 3–2 with three
saves and a 1.87 ERA, and 53 strikeouts in 43.1 innings, averaging 11.0 strikeouts per 9 innings. After the 2012 season
Baseball America ranked him the 5th-best prospect and best
curveball in the Indians organization, and the 13th best-prospect in the International League.
Cleveland Indians (2012–2018) On July 20, 2012, Allen made his Major League debut for the Cleveland Indians after being called up from Columbus He pitched an inning of relief giving up two
walks, no
runs, no
hits, and one strikeout. He struck out
Baltimore Orioles third baseman
Mark Reynolds for his first career strikeout. In 2013, Allen went 6–1 with a 2.43 ERA and 88 strikeouts in 70.1 innings, averaging 11.3 strikeouts per 9 innings. His 77 games pitched was second in the
American League, trailing only
Joel Peralta's 80 (and 2nd all-time for any Indians pitcher), and he was 2nd in the league in
errors committed by a pitcher (3), and 8th in
wild pitches (9). He tied for 6th in the 2013
BBWAA AL Rookie of the Year voting. Allen finished the season with 76 appearances (again 2nd in the American League; tied for 4th all-time for any Indians pitcher), a 6–4 record with a 2.07 ERA, 91 strikeouts (8th-most in a single-season by an Indians reliever), and 24
saves (9th) in innings, averaging 11.8 strikeouts per 9 innings. He struck out 87 batters (8th among AL relievers) in 68 innings, averaging 11.5 strikeouts per 9 innings. Allen lost his closer role to
Brad Hand after struggling in the month of August. He ended the season with 27 saves (6th in the AL) in 32 save chances in 70 appearances, as he was 4–6 with a 4.70 ERA, with 80 strikeouts in 67 innings, averaging 10.7 strikeouts per 9 innings. Through 2018, his 149 career saves were 9th of all major league active pitchers, topped all major league pitchers under 30 years of age, and topped all Cleveland Indians pitchers ever. He became a
free agent after the 2018 season. He began the season as the Angels closer, going 4/4 for the first couple of weeks of the season despite control issues. He was removed of the closer role on April 24 and later was placed on the injured list with a lumbar strain. He was
designated for assignment on June 15 after compiling a 6.26 ERA in 25 games, and was released on June 18.
Later career On June 22, 2019, the
Minnesota Twins signed Allen to a $500,000 minor league contract for the remainder of the 2019 season. He was released on July 31, 2019. In 11 games, two starts, 12 innings pitched between High-A
Fort Myers Miracle and Triple-A
Rochester Red Wings he went 0–2 with a 2.25 ERA and 11 strikeouts. On February 7, 2020, Allen signed a minor league deal with the
Texas Rangers. The Rangers released Allen on July 24. On July 31, Allen signed a minor league contract with the
Chicago Cubs. He was released by the organization on September 3, 2020. On February 17, 2021, Allen announced his retirement from professional baseball. ==Personal life==