In 2005, wanting to pursue a career in Major League Baseball (MLB), Girsch wrote an academic paper on the valuation of MLB draft picks and sent it to teams. John Mozeliak, the general manager of the St. Louis Cardinals, responded and hired him in 2006 as the coordinator for amateur scouting.[1] He was promoted to director of baseball development in 2008 and to assistant general manager in 2011.[4]
In 2017, the Cardinals promoted Mozeliak to the new position of president of baseball operations and promoted Girsch to general manager.[5][6] As general manager, he signed Paul DeJong, Paul Goldschmidt, and Matt Carpenter to contract extensions.[7][8][9] The Cardinals signed Girsch to a multi-year contract extension on October 17, 2022.[10] After the end of the 2024 season, Girsch was given the new title of Vice President of Special Projects.