The Cardinals recalled Cooper Hjerpe from Triple-A Memphis on September 6, 2026, and the left-hander is scheduled to make his major league debut on Sunday. It is a significant step for a 25-year-old pitcher whose path to St. Louis has been slowed by elbow surgery, Tommy John procedure recovery and long-standing control issues.
Hjerpe was the Cardinals' 22nd overall pick in the 2022 draft, and the organization has been patient as he moved through a development track interrupted by injuries. In 2023, he underwent surgery to remove loose bodies from his elbow. He then missed the 2025 season after a Tommy John procedure.
Even with the stops and starts, Hjerpe has continued to show the traits that made him a first-round selection. In 2024, he posted a 3.37 ERA and a 32.8% strikeout percentage rate across 93 1/3 innings between High-A and Double-A. But he also walked approximately 14% of hitters during the 2023-24 stretch, which remains the main question as he reaches the majors.
The Cardinals added Hjerpe to their 40-man roster in late November 2025, a move that helped protect him from the Rule 5 draft. That made him one of the more notable pitching prospects in the system to reach this point, and MLB Pipeline had ranked him as the 18th-best prospect in the organization.
A roster move in both directions
Hjerpe's promotion also came as part of a corresponding roster move involving Hancel Rincón. Six days after St. Louis selected Rincón's contract, he was sent back to Memphis after a difficult stint in the majors. That sequence of moves gave the Cardinals a fresh look at the bullpen while opening a path for Hjerpe's debut.
In recent Triple-A work, Hjerpe allowed seven earned runs in 1 1/3 innings, a reminder that the transition to the majors can be uneven even for pitchers with pedigree. Still, the Cardinals are giving him a chance now, and the immediate question is whether his strikeout ability can translate while he continues to manage the strike zone.
For St. Louis, the call-up offers a left-handed option and another chance to evaluate a pitcher whose talent has always been easy to see. The next step is simple enough: see how Hjerpe handles his first major league outing and whether he can begin turning prospect promise into a lasting role.
