He made his professional debut in 2012 with the rookie-level Gulf Coast Phillies, posting a 3.46 ERA in 12 games. He returned to the GCL Phillies the following year, registering a 2–3 record and 5.45 ERA with 26 strikeouts across 11 games (6 starts).[3] In 2014, he split time between the Low-A Williamsport Crosscutters and Single-A Lakewood BlueClaws. In 35 total games, Therrien posted a 4–1 record and 5.58 ERA with 54 strikeouts and 3 saves in 71.0 innings pitched.[4]
Therrien made 39 appearances in 2015, spending time with Lakewood and the High-A Clearwater Threshers. In 63.0 innings pitched, he recorded a 5–0 record and 1.43 ERA with 54 strikeouts and 5 saves.[5] He split the 2016 season between Clearwater and the Double-A Reading Fightin Phils, posting a cumulative 3–3 record and 2.59 ERA with 76 strikeouts and 5 saves in 55.2 innings of work across 39 appearances.[6] Therrien began the 2017 season with Reading, and was promoted to the Triple-A Lehigh Valley IronPigs after logging a 1.26 ERA with 7 saves in 21 games.[7]
On July 28, 2017, the Phillies promoted Therrien to the major leagues.[8] He made his MLB debut the following day against the Atlanta Braves surrendering a double and then retiring the next 3 batters.[9] He made 15 appearances for the Phillies, recording a 8.35 ERA with 10 strikeouts in 18.1 innings pitched.[10] On September 21, 2017, Therrien underwent Tommy John surgery, ending his season and wiping him out for the 2018 season as well.[11] On November 6, Therrien was removed from the 40-man roster and sent outright to Lehigh Valley, however he rejected the assignment and elected free agency.[12]
Los Angeles Dodgers
On November 24, 2017, Therrien signed a two-year minor league contract with the Los Angeles Dodgers organization.[13][14][15] He did not play during the 2018 season while recovering from his surgery. Therrien was invited to Spring Training with the Dodgers in 2019,[16] and was assigned to the Triple-A Oklahoma City Dodgers and placed on the injured list to begin the year. He did not play in a game for the organization and elected free agency following the season on November 4, 2019.[17]
Trois-Rivières Aigles
On May 8, 2023, after several years of inactivity, Therrien signed with the Trois-Rivières Aigles of the Frontier League.[18] In 10 games for the Aigles, Therrien struggled immensely to a 12.10 ERA with 13 strikeouts in 9+2⁄3 innings pitched. On June 27, Therrien was released by the Aigles.[19]
On May 1, 2024, Therrien re-signed with the Aigles for the 2024 season.[20]
