McGowan was called up to the majors for the first time on August 13, 2017 after the Mets traded infielder Neil Walker to the Milwaukee Brewers. McGowan was demoted to the minors on August 17 without having appeared in a game.[3]
On May 21, 2019, McGowan's contract was purchased by the Washington Nationals. He was assigned to the minor leagues and became a free agent at the conclusion of the 2019 season.[8]
Eastern Reyes del Tigre
In July 2020, McGowan signed on to play for the Eastern Reyes del Tigre of the Constellation Energy League (a makeshift 4-team independent league created as a result of the COVID-19 pandemic) for the 2020 season.
Lexington Legends
On February 26, 2021, McGowan signed with the Lexington Legends of the Atlantic League of Professional Baseball. He only appeared in 5 games during the season, posting a 4–1 record with a 4.50 ERA and 22 strikeouts. McGowan was released by the Legends on September 3, 2021.[9]
Tecolotes de los Dos Laredos
On June 24, 2023, McGowan signed with the Tecolotes de los Dos Laredos of the Mexican League.[10] In 9 games for the Tecolotes, he struggled to a 9.39 ERA with 4 strikeouts across 7+2⁄3 innings of work. On February 29, 2024, McGowan was released by Dos Laredos.[11]