OSU’s Cooper Hjerpe twirls 4 perfect frames in MLB debut
Published 9:50 am Monday, September 7, 2026
Hjerpe, the 2022 National Pitcher of the Year, strikes out 6 batters in MLB debut with St. Louis Cardinals on Sunday
Former Oregon State pitcher Cooper Hjerpe made his Major League debut Sunday, twirling four perfect innings for the St. Louis Cardinals.
He entered in the fourth inning of St. Louis’ matchup against the Colorado Rockies, striking out six batters without allowing one to reach base against him. The Cardinals trailed, 5-1, when Hjerpe entered, though the club rallied for a 10-8 win behind the left-hander’s quartet of shutout frames.
“It was unbelievable,” Hjerpe, who earned the win, told MLB.com after the game. “It was a great experience, great debut. Can’t get much better than that. I felt really good from the get-go. Felt like everything was moving really well and pounding the zone.”
Hjerpe, 25, spent three seasons at Oregon State and started 33 of the 41 games he appeared in. He was Perfect Game’s 2022 Pitcher of the Year and a finalist for the Golden Spikes Award, presented to college baseball’s top player, that same year. Hjerpe tallied 192.1 innings over his Beavers career, posted a 15-9 record and a career 3.37 ERA.
He’s the 47th former Oregon State player to make their Major League debut and was ranked the 18th-best prospect in St. Louis’ organization.
The Cardinals selected him with the 22nd pick of the first round in the 2022 MLB draft, signing the left-hander for $3.1 million. He made his debut Sunday after four years in St. Louis’ organization, with numerous elbow injuries (a 2023 surgery to remove “loose bodies” from his elbow and a 2024 Tommy John surgery) delaying his track to the major leagues.
After missing the entirety of the 2025 season, Hjerpe returned to the mound this June and was promoted to St. Louis’ Triple-A affiliate, the Memphis Redbirds, in early August. Hjerpe posted a 0.95 ERA in five starts (19 innings) for Memphis, allowing only 10 hits, issuing 17 walks and punching out 27 batters.
Cardinals manager Oli Marmol told media members after the game that the club “will not use (Hjerpe) as a reliever” this season. Though he’ll pitch out of the bullpen as a piggyback starter, St. Louis intends to keep the lefty on a starter’s schedule.