St. Louis Cardinals Walsh signed with St. Louis and made his professional debut with the
Johnson City Cardinals of the
Rookie-level Appalachian League, going 5–0 with a 0.95 ERA over innings. He spent the 2018 season with the
Peoria Chiefs of the
Single–A Midwest League and the
Palm Beach Cardinals of the
High–A Florida State League, appearing in 25 games (24 starts) with both clubs in which he went 9–5 with a 2.51 ERA and 116 strikeouts. Walsh appeared in only two games in 2019 due to injury, and did not play a game in 2020 due to the cancellation of the minor league season because of the
COVID-19 pandemic. In 2021, Walsh missed time due to injury, but still appeared in 17 games with the
Springfield Cardinals of the
Double-A Central and the
Memphis Redbirds of the
Triple-A East, going 2–2 with a 2.86 ERA and 34 strikeouts over 22 relief innings. He was selected to play in the
Arizona Fall League for the
Glendale Desert Dogs after the season. On November 19, 2021, the Cardinals selected Walsh's contract and added him to their
40-man roster to protect him from the
Rule 5 draft. He returned to Memphis to begin the 2022 season. On May 11, the Cardinals promoted Walsh to the major leagues. In three games during his rookie campaign, he struggled to a 13.50 ERA with 5 strikeouts in innings of work. Walsh was optioned to Triple-A Memphis to begin the 2023 season. In 27 games for Memphis, he worked to a 5.28 ERA with 34 strikeouts and 4
saves in innings pitched. On July 23, Walsh was placed on the injured list with an unspecified nerve issue in his arm. Following
Taylor Motter's promotion the same day, Walsh was released by the Cardinals.
Atlanta Braves On February 2, 2024, Walsh signed a minor league contract with the
Atlanta Braves. In 11 relief outings for the Triple–A
Gwinnett Stripers, he recorded a 2.31 ERA with 8 strikeouts across innings pitched. On June 1, Walsh was released by the Braves organization.
Ogden Raptors On August 5, 2025, Walsh signed with the
Ogden Raptors of the
Pioneer League. In five appearances for Ogden, he recorded a 3.60 ERA with nine strikeouts over five innings of work. Walsh was released by the Raptors on August 22. ==References==