Ross Detwiler, a left-handed pitcher, embarked on his Major League Baseball career after being selected by the Washington Nationals in the first round of the 2007 MLB Draft. Detwiler, who played college baseball at Missouri State University, quickly rose through the ranks of the Nationals' farm system, making his MLB debut on September 7, 2007.

In the early years of his career, Detwiler's role with the Nationals fluctuated between starting pitcher and reliever. By 2012, he had secured a spot in the starting rotation, contributing to the Nationals' first-ever National League East division title. That season, Detwiler posted a 10-8 record with a 3.40 ERA over 27 starts, showcasing his ability to handle the pressures of a starting role. His performance in the 2012 National League Division Series was particularly noteworthy, as he pitched six strong innings in Game 4 against the St. Louis Cardinals, helping the Nationals force a decisive Game 5.

The following seasons saw Detwiler's role shift once again. In 2014, he transitioned to the bullpen, where he appeared in 47 games for the Nationals. However, his performance was less consistent, and he finished the season with a 4.00 ERA. In December 2014, Detwiler was traded to the Texas Rangers, marking the beginning of a journeyman phase in his career.

Detwiler's time with the Rangers in 2015 was challenging, as he struggled to find his footing, resulting in a 7.12 ERA over 17 appearances. Midway through the season, he was designated for assignment and subsequently traded to the Atlanta Braves. His stint with the Braves was brief, and he was released after posting a 7.71 ERA in seven games.

In 2016, Detwiler signed a minor league contract with the Cleveland Indians, eventually making it back to the majors for a short period. Later that year, he joined the Oakland Athletics, where he made seven starts and recorded a 6.14 ERA. Despite the setbacks, Detwiler continued to pursue opportunities in the majors, signing with the Chicago White Sox in 2017. However, he spent most of the season in the minors.

Detwiler's perseverance paid off in 2019 when he returned to the majors with the White Sox, appearing in 18 games and starting 12. He recorded a 6.59 ERA, but his ability to fill multiple roles on the pitching staff proved valuable. In 2020, Detwiler remained with the White Sox, pitching primarily out of the bullpen during the shortened season and posting a 3.20 ERA over 16 appearances.

The Miami Marlins signed Detwiler for the 2021 season, where he continued to serve as a versatile arm out of the bullpen. He appeared in 46 games for the Marlins, recording a 4.96 ERA. Later that year, he was claimed off waivers by the San Diego Padres, where he finished the season.

Throughout his career, Detwiler demonstrated adaptability, transitioning between starting and relieving roles as needed.