He also played in MLB for the Texas Rangers, Atlanta Braves, Cleveland Indians, Oakland Athletics, Seattle Mariners, Chicago White Sox, Miami Marlins, San Diego Padres, and Cincinnati Reds.

[7] Detwiler was the fifth pitcher taken by the Washington Nationals/Montreal Expos franchise in the first round of the draft in the last six years following Clint Everts, Chad Cordero and Bill Bray in 2002, 2003 and 2004, respectively, and Colton Willems taken in 2006.

On September 7, 2007, he made his MLB debut, pitching one hitless inning in relief against the Atlanta Braves, striking out one.

[10] He joined Cordero and Ryan Zimmerman as the third member of the Nationals franchise to be called up to the major leagues in the same year that he was drafted.

[12] Detwiler made his return to MLB play in July 2011 after recovering from hip surgery, and he remained in rotation for the remainder of the 2011 season.

[14] Although he pitched effectively, the return of Chien-Ming Wang from injury put Detwiler in the long relief role in late May.

[21] On December 12, 2014, the Nationals traded Detwiler to the Texas Rangers for Chris Bostick and Abel De Los Santos.

[23] Upon his return to the active roster, Detwiler made ten appearances out of the bullpen, and saw his ERA climb to 7.12.

On July 17, 2016, Detwiler was traded to the Oakland Athletics in exchange for cash considerations, and was assigned to the Triple-A Nashville Sounds.

[32] On January 18, 2017, Detwiler signed a minor league contract with the Athletics that included an invitation to spring training.

[37] On March 14, 2018, Detwiler signed with the York Revolution of the independent Atlantic League of Professional Baseball.

[40] He took the mound in relief that night, giving up three runs in six innings to the defending World Series Champion Houston Astros.

Detwiler became a free agent following the season, but later re-signed with the White Sox to a minor league deal.

[47] With the 2020 Chicago White Sox, Detwiler appeared in 16 games, compiling a 1–1 record with 3.20 ERA and 15 strikeouts in 19.2 innings pitched.

[54] He was assigned to the Triple-A Louisville Bats to begin the year, where he posted a 3.86 ERA and 1.57 WHIP in 7.0 innings across 7 appearances.

[55] On August 29, Detwiler became the 450th unique pitcher to surrender a home run to Albert Pujols, breaking the record previously set by Barry Bonds.

[6] As St. Louis natives, Detwiler and his family were avid fans of the Cardinals, Blues, and the now re-located Rams.