Mitchell “Mitch” Neunborn is an Australian representative right-handed baseball pitcher in the Philadelphia Phillies organisation. Listed by the provider as an inactive Philadelphia Phillies relief pitcher, he has primarily worked as a starter and bulk-inning pitcher in affiliated minor-league baseball. Neunborn represented Australia at the 2023 World Baseball Classic and made a significant professional breakthrough after the tournament, signing with Philadelphia in June 2023. As of August 18,…
Neunborn was born on June 27, 1997, in Johannesburg, South Africa, and developed his baseball career through the Australian system. He attended North Iowa Community College in the United States and played Australian Baseball League baseball for the Perth Heat and Adelaide Giants. Baseball Australia identifies West Torrens as his Australian club in its 2026 Team Australia material.
His early professional path was unconventional and persistent. Before reaching affiliated baseball, Neunborn played in Australia and worked multiple jobs while continuing to pursue professional opportunities. Baseball Australia has reported that he underwent two major surgeries during his career; the specific procedures and dates are not publicly confirmed in the available sources.
Neunborn pitched for Australia at the 2023 World Baseball Classic, delivering important performances in victories over Korea and Czechia. The tournament accelerated his professional prospects, and he signed with the Philadelphia Phillies on June 5, 2023. He began his affiliated career with the Jersey Shore BlueClaws in the South Atlantic League, recording a 3.38 ERA and 54 strikeouts in 42.2 innings across 16 appearances in 2023. He was named South Atlantic League Pitcher of the Week for the week of September 3, 2023, and later pitched for the Scottsdale Scorpions in the Arizona Fall League.
In 2024, Neunborn began with Jersey Shore and later advanced to the Double-A Reading Fightin Phils. Across two minor-league teams, he posted a 3.15 ERA, seven wins and 96 strikeouts in 91.1 innings. His Jersey Shore work was particularly strong: a 2.39 ERA, 70 strikeouts and a 1.09 WHIP in 67.2 innings. He continued through the Phillies system in 2025, splitting time between Reading and the Triple-A Lehigh Valley IronPigs and making 32 total appearances.
The 2026 season included movement between Philadelphia's major-league roster designation and its minor-league affiliates. He was assigned to Philadelphia on February 22, 2026, but the available official game notes state that he did not make his Major League debut. He was subsequently assigned to Reading and Lehigh Valley, with rehabilitation assignments to the Florida Complex League Phillies and Jersey Shore after beginning the season on the injured list. His provider status was inactive on August 18, 2026. Neunborn remains an Australian international pitcher and a member of the Phillies organisation, but there is no verified evidence that he has appeared in an MLB regular-season game.
Neunborn's first major documented breakthrough came at the 2023 World Baseball Classic, where he produced key performances for Australia in wins over Korea and Czechia. Baseball Australia described the tournament as accelerating his professional career. He signed with the Philadelphia Phillies on June 5, 2023, shortly after the tournament.
In 2023 with Jersey Shore, Neunborn recorded a 3.38 ERA, 54 strikeouts, 14 walks and a 0.94 WHIP in 42.2 innings. In 2024 across Jersey Shore and Reading, he posted a 3.15 ERA, seven wins and 96 strikeouts in 91.1 innings. His 2024 Jersey Shore season included a 2.39 ERA, 70 strikeouts and a 1.09 WHIP in 67.2 innings. He was named South Atlantic League Pitcher of the Week for the week of September 3, 2023. Official Phillies material also identified his 2024 ERA as second among Phillies minor-league pitchers with at least 75 innings.
Representing Australia at the 2023 World Baseball Classic and contributing to wins over Korea and Czechia was the defining early moment of Neunborn's professional career. His signing with the Philadelphia Phillies soon afterwards marked his entry into affiliated professional baseball. He also earned South Atlantic League Pitcher of the Week recognition in September 2023 and reached the Arizona Fall League with Scottsdale later that year.