Houston Astros Bielak signed with Houston and made his professional debut with the
Gulf Coast League Astros. After two scoreless appearances, he was promoted to the
Tri-City ValleyCats where he finished the season with a 1–1 record and a 0.92 ERA in eight games (four starts). In 2018, Bielak began the season with the
Buies Creek Astros and was named a
Carolina League All-Star; he was promoted to the
Corpus Christi Hooks in June. In 25 games (17 starts) between the two clubs, he went 7–8 with a 2.23 ERA and a 1.15 WHIP. In 2019, Bielak returned to Corpus Christi to begin the season and was promoted to the
Round Rock Express in May. Over 23 games (twenty starts), Bielak went 11–4 with a 4.22 ERA, striking out 119 over innings. On July 27,
2020, Bielak's contract was selected to the 40-man roster. He made his MLB debut that day against the
Seattle Mariners and was the winning pitcher in an 8–5 contest. Bielak finished the 2020 season with Houston with a 6.75 ERA over 32 innings. In
2021, Bielak went 3–4 while appearing in 28 games (two starts). He pitched fifty innings and struck out 46 batters while walking 21; he had a WHIP of 1.380 and an ERA of 4.50. Bielak made five appearances for Houston in
2022, spending the majority of the season with the Triple-A
Sugar Land Space Cowboys. In innings pitched, he recorded a 3.65 ERA with 12 strikeouts. Bielak was optioned to Triple-A Sugar Land to begin the
2023 season. The Astros recalled him to the major league roster on April 30, 2023. On May 19, Bielak earned his first win of the season with a career-high nine strikeouts versus the
Oakland Athletics. He established a number career highs at the major league level in 2023, including in games won with a 5–6 record, games stated (13) and innings pitched (80). He posted a 3.83 ERA, 5.19
FIP, 86 hits, 36 walks, and 12 home runs allowed, 1.525
walks plus hits per inning pitched (WHIP), and 7.0
strikeouts per nine innings pitched (K/9, 62 total). Bielak made 10 appearances for Houston in
2024, compiling a 5.71 ERA with 9 strikeouts across innings pitched. On May 11, 2024, Bielak was
designated for assignment by the Astros.
Oakland Athletics On May 16, 2024, Bielak was traded to the
Oakland Athletics in exchange for cash considerations. In three games for Oakland, he recorded a 3.18 ERA with three strikeouts across innings pitched. Bielak was designated for assignment by the Athletics following the promotion of
Jack O'Loughlin on May 25. He cleared waivers and was sent outright to the Triple–A
Las Vegas Aviators on May 29. On September 8, the Athletics selected Bielak's contract, adding him to their active roster. After three more appearances, he was designated for assignment by Oakland on September 22. He cleared waivers and was sent outright to Triple–A Las Vegas a second time on September 25. Bielak elected free agency on October 15.
Arizona Diamondbacks On February 25, 2025, Bielak signed a minor league contract with the
Arizona Diamondbacks. In two starts for the Triple-A
Reno Aces, he posted a 1-0 record and 2.79 ERA with five strikeouts across innings pitched. Bielak was released by the Diamondbacks organization on May 10. On May 12, it was announced that Bielak had undergone season-ending shoulder surgery prior to his release.
Houston Astros (second stint) On March 10, 2026, Bielak signed with the
Tecolotes de los Dos Laredos of the
Mexican League. However, prior to the start of the season on April 14, Bielak signed a minor league contract with the
Houston Astros. ==References==