The Cardinals placed pitching prospect Sem Robberse on the full-season injured list in the minor leagues today. The club announced to reporters, including Jeff Jones of the Belleville News-Democrat, that the righty has undergone Tommy John surgery. He’ll miss the remainder of this season and part of 2026 as well.
Robberse, now 23, was one of two young pitchers the Cardinals acquired from the Blue Jays in the 2023 deadline deal which sent Jordan Hicks to Toronto. Robberse was set to be eligible in the Rule 5 draft a few months later, but the Cards protected him by adding him to their 40-man roster that November.
The young Netherlands-born righty has generally been a serviceable starter in the minors. From 2021 to 2024, he tossed 414 1/3 innings, allowing 4.04 earned runs per nine. His 22.5% strikeout rate and 8.9% walk rate in that span were both fairly average numbers. He also got ground balls on close to half of the balls in play he allowed.
This year, he got out to a rough start, posting a 7.36 ERA over four Triple-A outings. However, that seems to have been mostly bad luck. His .447 batting average on balls in play and 61.6% strand rate in that small sample were both to the unfortunate side. Meanwhile, his 24.7% strikeout rate and 46.8% ground ball rate were both strong numbers. His 10.4% walk rate was on the high side but not egregiously so.
Regardless, Robberse is not going to get a chance to correct those numbers, an unfortunate blow for him and the team. It’s not a huge deal in the short term. The St. Louis rotation is so healthy right now that Steven Matz has been bumped to the bullpen multiple times, despite strong results. Michael McGreevy is stuck in Triple-A even though he’s putting up good numbers there.
Still, depth can disappear fast and this is the second hit the Cards have taken in that department. Cooper Hjerpe, one of the club’s top pitching prospects, required his own Tommy John surgery last month.
In the longer term, this will cloud Robberse’s path to making it to the majors. The Cards are slated to lose Matz, Miles Mikolas and Erick Fedde to free agency this winter. That would leave them with a projected 2026 rotation of Sonny Gray, Andre Pallante and Matthew Liberatore, with two potential rotation spots open.
Instead of competing for a role in the starting mix, Robberse will be rehabbing from his surgery. He’s currently in his second of three option years. That means 2026 could be his final option year, if he sticks on the 40-man roster through the upcoming offseason. He probably won’t be fully healthy until midway through that 2026 season. The Cards could call him up and put him on the major league 60-day IL at some point, if they so choose. Doing so would open a 40-man roster spot but it would also involve Robberse earning major league pay and service time.
Photo courtesy of Jim Rassol, Imagn Images