On September 7, 2021, Baumann made his major league debut with the Orioles against the Kansas City Royals at Oriole Park at Camden Yards.[9] In his debut he pitched 3+2⁄3 innings and allowed two hits and one walk.[10] Baumann struck out one batter and retired 11 of the 14 batters he faced. He also earned his first Major League win. In his rookie campaign, Baumann recorded a 9.90 ERA in four games.
Baumann pitched in 14 contests for Baltimore in 2022, registering a 4.72 ERA with 23 strikeouts across 34+1⁄3 innings of work.[11] On March 16, 2023, it was announced that Baumann would shift to a short-relief role rather than being a starter.[12] He made 60 appearances out of the bullpen for the Orioles, compiling a 10–1 record and 3.76 RRA with 61 strikeouts across 64+2⁄3 innings pitched.[13]
In 2024, Baumann made 17 relief appearances for Baltimore, logging a 3.44 ERA with 16 strikeouts across 18+1⁄3 innings pitched. On May 18, 2024, Baumann was designated for assignment by the Orioles.[14]
Seattle Mariners
On May 22, 2024, Baumann and Michael Pérez were traded to the Seattle Mariners in exchange for Blake Hunt.[15] In 18 appearances for Seattle, he logged a 5.51 ERA with 16 strikeouts across 16+1⁄3 innings pitched. Baumann was designated for assignment by the Mariners on July 19.[16]
San Francisco Giants
On, July 21, 2024, Baumann was claimed off waivers by the San Francisco Giants.[17] He made one appearance for the Giants, allowing two runs and recording two outs in a blowout victory against the Colorado Rockies on July 26. The following day, Baumann was designated for assignment.[18]
Los Angeles Angels
On July 30, 2024, Baumann was traded to the Los Angeles Angels in exchange for cash considerations.[19] In 10 games for the Angels, he worked to a 6.75 ERA with 7 strikeouts across 9+1⁄3 innings. Baumann was designated for assignment following the promotion of Ryan Zeferjahn on August 23.[20]
Miami Marlins
On August 25, 2024, Baumann was claimed off waivers by the Miami Marlins.[21] He tied Oliver Drake's record for appearing with five different MLB teams in a single season.[22]
Personal life
His older brother, Nick, also played baseball and football at Mahtomedi and starred on the defensive line for the Concordia Cobbers.[1] He married his fiancée Nicole in the offseason following 2023 season. The wedding took place in Florida, where he resides in the offseason.