Cardinals’ top 10 moments of 2026, No. 8: Cooper Hjerpe perfect in long-awaited debut

When the St. Louis Cardinals drafted Cooper Hjerpe back in 2022, they expected to get a fast-rising starter in their system who could impact their big-league rotation in a short time. While the wait took a lot longer than they wanted, it's safe to say he was worth the wait.

Counting down the 10 best moments of the 2026 season for the Cardinals on both the Dealin' the Cards podcast and Redbird Rants, Hjerpe's MLB debut slots in as the eighth best moment, with the dynamic left-hander throwing four perfect innings of work against the Colorado Rockies.

Cooper Hjerpe showed the Cardinals how high his upside is in his debut

Hjerpe was in his bag against the Rockies, striking out six batters during those four perfect innings of relief, piggybacking Cardinals starter Kyle Leahy.

Hjerpe's four innings of perfect work were the longest stretch of perfection in a debut since Max Kranick in 2021 and Max Scherzer during his MLB debut. It's not every day you see a young arm that dominant in their first taste of big league action, and it's truly a glimpse at why Hjerpe is such an intriguing arm.

Overall, Hjerpe's debut season saw him make four appearances, posting a 4.38 ERA with 15 strikeouts over 12.1 innings of work. All of Hjerpe's work came out of the bullpen, and while that could end up being his role in the future, he's going to have every opportunity to become a starter for the Cardinals long-term.

Hjerpe is such a unique arm, one whose pitches are deceptive because of his unique arm angles and release points, so while the velocity may not pop on the radar gun, it plays up because of how special he is. Throughout his time in the minor leagues, Hjerpe constantly had hitters on their heels and going down swinging or looking, with injuries being the only reason he hasn't already been a staple of the Cardinals rotation moving forward.

How the Cardinals handle Hjerpe next year will be very interesting. He threw just 52.1 innings of work in his return from Tommy John surgery this year, tied with his career high in innings with the Cardinals organization since being drafted. As we saw with Kyle Leahy this year, the Cardinals are going to be cautious in how they build up arms and their workload, and so they'll likely have some kind of plan in place with Hjerpe next year too.

For years, the Cardinals struggled to produce capable arms for their Major League rotation, and this year alone, we saw Hjerpe and Quinn Mathews impress in their debuts, joining Leahy, Michael McGreevy, and Andre Pallante as quality big starters moving forward.

Hunter Dobbins and Richard Fitts will be back from their injuries to join that group in the future, while the likes of Liam Doyle, Tanner Franklin, Jurrangelo Cijntje, Brandon Clarke, Mason Molina, Yhoiker Fajardo, Jacob Odle, Tegan Kuhns, and more are developing down on the farm.

Hjerpe's debut was special, and if things keep going in the Cardinals' favor, they'll have a lot more debuts to be excited about in 2027 and beyond.

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