Mullenbach joins the Saltdogs, for his first season in 2025. After playing four years in college at Lincoln Memorial, Mullenbach caught on in the Mets and Twins organizations, reaching Triple-A, St. Paul. He has spent the last two seasons in the American Association with Lake Country, before arriving in Lincoln, via a trade. During his minor league career, he has accumulated seven saves and 125 strikeouts, over four seasons.

2024: Mullenbach pitched in 37 games for Lake Country, going 2-4 with a 3.20 ERA, and four starts. In 64.2 innings pitched, Mullenbach struck out 41 batters.

2023: Went 3-0 for Lake Country, with a 2.61 ERA, in 38 appearances. In 38.0 innings pitched, he struck out 27 batters.

2022: Began the season with the St. Paul Saints (Triple-A MIN), in the International League. He was 0-0 with a 9.00 ERA, in two appearances. In 3.0 innings pitched, he struck out three batters. Mullenbach appeared in 20 games for the Cedar Rapids Kernels (High-A MIN), in the Midwest League. He was 1-1 with a 1.29 ERA. In 28.0 innings pitched, he struck out 26 batters. He finished the season with the Fort Myers Mighty Mussels (Low-A MIN), in the Florida State League. He was 3-0 with a 2.12 ERA. Mullenbach appeared in ten games and recorded one save. In 17.0 innings pitched, he struck out 20 batters.

2021: Mullenbach began the season with St. Paul, going 0-0 with a 0.00 ERA. In one appearance, he pitched 2.0 innings. He had seven appearances with Fort Myers, in the Low-A Southeast League, going 1-0 with a 4.70 ERA. He had one start and recorded one save. In 15.1 innings pitched, he struck out 19 batters. Mullenbach had nine appearances for the Twins in the Florida Complex League. He was 1-1 with a 3.44 ERA. In 18.1 innings pitched, he struck out 18 batters. He concluded the season with the Lake Erie Crushers, in the Frontier League. He was 0-0 with a 6.75 ERA. In two appearances, he pitched 4.0 innings and struck out five batters.

2020: Did Not Play

2019: Finished his senior season at Lincoln Memorial, going 3-6 with a 5.38 ERA. In 14 starts, he recorded three complete games, with two shutouts. In 73.2 innings pitched, he struck out 92 batters. Mullenbach began his professional career with the Brooklyn Cyclones (Low-A NYM), in the New York-Pennsylvania league. He was 1-5 with a 2.84 ERA. In 19 appearances, he recorded five saves. In 25.1 innings pitched, he struck out 26 batters.

2018: In his junior season with Lincoln Memorial, Mullenbach as 7-3 with a 4.82 ERA. In 16 appearances, he recorded eight starts with two complete games and one shutout. In 56.0 innings pitched, he struck out 65 batters.

2017: Appeared in 14 games with seven starts for Lincoln Memorial, going 0-2 with a 7.24 ERA. In 32.1 innings pitched, he struck out 32 batters.

2016: In his freshman year at Lincoln Memorial, he was 1-6 with a 7.16 ERA. In 16 appearances, he had seven starts. In 32.2 innings pitched, he struck out 35 batters.