Miami Marlins To begin his professional baseball career, Guenther was assigned to the
Gulf Coast League Marlins of the
Gulf Coast League in 2017. In three starts and four total games with the GCL Marlins, Guenther only allowed one
run, five hits, and eleven
strikeouts in 11 innings. Guenther was quickly promoted to the
Batavia Muckdogs of the
New York-Penn League. In 40 innings with the Muckdogs, Guenther posted a 1–4 record with thirty-three strikeouts and a 3.83 ERA. For the 2018 season, Guenther was assigned to the
Jupiter Hammerheads of the
Florida State League. Early struggles with the Hammerheads had Guenther demoted to the
Greensboro Grasshoppers of the
Single-A South Atlantic League. Guenther also appeared in a rehab game with the GCL Marlins in 2018. In 2019, Guenther appeared with the
Clinton LumberKings of the
Midwest League and with the Jupiter Hammerheads. Guenther did not play in a game in 2020 due to the cancellation of the minor league season because of the
COVID-19 pandemic. To begin the 2021 season, Guenther was assigned to the
Pensacola Blue Wahoos of
Double-A South. In innings with Pensacola, Guenther posted a 1–0 record with a 1.02 ERA and 28 strikeouts. On June 8, Guenther was promoted to the
Jacksonville Jumbo Shrimp of
Triple-A East. On August 4, Guenther was called up by the Marlins and made his debut 2 days later. On April 7, 2022, Guenther underwent
Tommy John surgery, ending his season before it began.
Detroit Tigers On November 2, 2022, Guenther was claimed off waivers by the
Detroit Tigers. On November 15, he was removed from the
40-man roster and sent outright to the Triple–A
Toledo Mud Hens. Guenther began the 2024 campaign with Toledo, recording a 3.86 ERA with 46 strikeouts and 3
saves across innings pitched. On August 1, 2024, the Tigers selected Guenther's contract, adding him to their active roster. He made his season debut later that day against the
Kansas City Royals, coming in with two outs in the 8th inning in relief of
Brenan Hanifee. Guenther finished the 8th inning and continued into the 9th, ultimately giving up 1 hit, 1 earned run, and 0 walks over innings.In 17 appearances for Detroit, Gunther logged a 3-0 record and 0.86 ERA with 12 strikeouts across 21 innings pitched. Guenther was optioned to Triple-A Toledo to begin the 2025 season. On July 6, 2025, Guenther was placed on the 60-day injured list after undergoing a left hip
arthroscopy. In nine appearances for Detroit, he had logged an 0-1 record and 5.23 ERA with eight strikeouts across innings pitched. Guenther was designated for assignment by the Tigers on November 18. On November 21, he was non-tendered by Detroit and became a free agent. On December 16, 2025, Guenther re-signed with the Tigers on a minor league contract. ==References==