Another late-inning collapse against the Twins turned a potential sweep into another painful reminder. The frustration traveled with the club to San Diego, where the bullpen’s problems followed them into the series finale. Chris Roycroft couldn’t locate his stuff or limit damage against the Padres. Shortly after, the Cardinals designated him for assignment and selected Max Rajcic’s contract for his MLB debut.
Rajcic earned the nod. The bigger question now is who follows.
Luis Gastelum has done everything the organization could have asked for at Triple-A Memphis. The 24-year-old right-hander, ranked the Cardinals’ No. 21 prospect by MLB Pipeline, has been one of the most effective relievers in the system this season. His numbers have turned heads in St. Louis and beyond.
Kareem Haq, who covers the Cardinals’ minor league affiliates, put it plainly: “Gastelum’s allergy to runs has been his providence this season. The right-hander is known for his UFO changeup.”
That changeup is the engine. MLB Pipeline explained exactly why it plays so well:
“Gastelum’s success to this point stems from one pitch: his low-80s changeup. It’s a mesmerizing offering with a negative induced vertical break and plenty of armside run. It practically works like a left-handed breaking ball, but instead emerges from the 6-foot-2 right-hander’s low three-quarters delivery. Because of that action, the cambio was even more effective against righties than lefties last year, with a 64 percent whiff rate against same-side bats. (Not that lefties fared that much better.) Gastelum can throw a mid-90s fastball, but with ordinary movement, it only works to set up his beast of a change. He’ll occasionally work in a mid-80s sweeper too for something with big gloveside movement.”
The combination of low slot, armside run on the change, and the ability to miss bats at a high rate gives Gastelum a weapon that translates. In 2026 at Memphis he has posted a 2.68 ERA and 0.97 WHIP in 37 innings, striking out 39 batters. Those are the kinds of results that force a conversation.
The Cardinals’ bullpen entered the season with legitimate uncertainty. Riley O’Brien’s hot start has cooled, leaving the group thin in high-leverage and bulk-innings roles. The recent losses in close games have made the lack of reliable options impossible to ignore. Roycroft flashed arm talent at times, but the 13.50 ERA in his four innings this season showed the gap between stuff and results against big-league hitters.
Chaim Bloom’s philosophy has been consistent. This is runway season. The front office would rather give internal options every opportunity before turning to external additions in July. That approach makes a pitcher like Gastelum even more interesting. It does not matter how refined he looks on the first day in the big leagues. The runway exists, and the arm talent is real.
One more swing-and-miss reliever who can keep runs off the board changes the math in the eighth and ninth innings. The Cardinals have seen enough from their farm system this year to know some of their best answers are already inside the organization. Gastelum is not a finished product, but he is ready for the chance to prove he belongs.
The bullpen has been the clearest weakness on the roster. The organization now has a decision to make.