JUST IN: After Rincón’s Rocky Debut, Cardinals Hand Hjerpe His Long-Awaited MLB Opportunity

The St. Louis Cardinals have promoted left-handed pitching prospect Cooper Hjerpe from Triple-A Memphis, giving the highly regarded 25-year-old an opportunity to make his long-awaited major-league debut. The club announced the move Sunday, with right-hander Hancel Rincón being optioned back to Memphis in the corresponding roster transaction.

Hjerpe is scheduled to make his first MLB appearance Sunday against the Colorado Rockies. According to Derrick Goold of the St. Louis Post-Dispatch, he will follow right-handed starter Kyle Leahy in the game.

The promotion represents an important milestone for Hjerpe, who has spent several seasons working his way through the Cardinals’ minor-league system. St. Louis selected the Oregon State product with the 22nd overall pick in the 2022 MLB Draft, viewing his unusual delivery and strikeout ability as potentially valuable weapons at the professional level.

Hjerpe initially showed plenty of promise after entering the organization. Through 2024, he recorded a 3.37 ERA and struck out 32.8% of opposing hitters across 93⅓ innings between High-A and Double-A. However, his development was slowed by two persistent concerns: command and injuries.

During the 2023 and 2024 seasons, Hjerpe walked roughly 14% of the batters he faced. He also underwent elbow surgery to remove loose bodies in 2023, and the subsequent recovery process created further obstacles in his development. His injury problems became even more significant when he underwent Tommy John surgery, forcing him to miss the entire 2025 season.

Because Hjerpe was recovering from surgery and could have been exposed to the Rule 5 Draft, the Cardinals added him to their 40-man roster in late November. At that point, he was still working his way back, but his return to competitive baseball has provided encouraging signs.

This season, Hjerpe has posted a combined 3.00 ERA over 42 innings while pitching across three minor-league levels. His performance became particularly impressive after reaching Triple-A Memphis, where he has allowed an extraordinary 0.95 ERA through his first 19 innings.

His statistical profile remains intriguing. Hjerpe does not rely on overpowering velocity, with his fastball averaging around 91 mph, but his unusual sidearm delivery and combination of pitches have helped him generate swings and misses. Along with his fastball, he has used a sweeper and changeup to produce a 34.2% strikeout rate against Memphis hitters.

The major concern, however, remains his command. Hjerpe has walked 21.5% of the batters he has faced at Triple-A, an extremely high figure that could present a significant challenge against major-league hitters.

MLB Pipeline currently ranks Hjerpe as the Cardinals’ No. 18 prospect and continues to identify his control as one of the biggest questions surrounding his future. His ability to miss bats gives him an obvious weapon, but limiting free passes will be critical if he is going to establish himself as a reliable major-league pitcher.

Hjerpe’s promotion also comes immediately after Rincón’s brief and eventful stint with St. Louis.

The Cardinals selected Rincón’s contract only six days ago, but the 24-year-old right-hander has already been returned to Memphis after a difficult introduction to the majors. Across his first two appearances, Rincón surrendered seven earned runs in just 1⅓ innings.

Those numbers, however, were almost overshadowed by the bizarre controversy surrounding his MLB debut.

After Rincón entered Friday’s game against Colorado, home-plate umpire and crew chief Doug Eddings instructed the rookie to straighten his baseball cap. Rincón had been wearing the cap at an angle, and the unusual exchange quickly became a major storyline.

Rockies catcher Hunter Goodman was initially reported to have raised concerns about Rincón’s hat, but Goodman denied making any such complaint. The disagreement eventually contributed to a confrontation between Eddings and Cardinals manager Oliver Marmol, who was ejected while arguing with the umpire.

The incident continued to generate attention the following day when several Cardinals players wore their caps crookedly in what appeared to be a show of support for their teammate. Some Rockies players reportedly joined the gesture as well.

The situation ultimately cooled when Eddings apologized directly to Rincón before Saturday’s game.

While Rincón struggled statistically during his brief major-league opportunity, the Cardinals will now turn their attention to Hjerpe, whose promotion gives the club another young pitching option as the regular season enters its final stretch.

For Hjerpe, Sunday’s appearance represents the culmination of a long and difficult road back from injury. After being sidelined for an entire season and working through significant command concerns, he now has an opportunity to prove that his unusual delivery, pitch mix and ability to generate strikeouts can translate against major-league competition.

The Cardinals will be hoping that Hjerpe can provide quality innings as they continue their push toward the postseason, while the rookie himself will be looking to turn an unexpected opportunity into a permanent place on the major-league roster.