#11 - RHP Sem Robberse
Scouting grades: Fastball: 40 | Sweeper: 60 | Changeup: 55 | Cutter: 45 | Command: 50 | Overall: 45
Background:
Robberse was the headliner of the return package for Jordan Hicks at the 2023 trade deadline. Originally signed by the Blue Jays out of the Netherlands in 2019, Robberse quickly climbed their system and has consistently been one of the youngest players at every level he’s pitched at. Despite regularly facing older, more advanced competition, he’s managed to hold his own at each stop.
Scouting Report:
Robberse’s raw stuff doesn’t jump off the page—his fastball sits in the low 90s and features below-average shape, with 15–16 inches of induced vertical break from a steep, over-the-top 5.9-foot release height. However, he offsets that with two exciting secondary offerings in his sweeper and changeup.
His changeup is his primary weapon against left-handed hitters. Though it only comes in about four MPH slower than his fastball, it tunnels well thanks to roughly 10 inches of vertical and 8 inches of arm-side separation off the heater. It was his most-used pitch against lefties (28%) and delivered strong results, generating over 40% whiff and chase rates.
In 2024, Robberse tweaked his fastball shape to give it more of a distinct cut-ride profile. That adjustment, combined with optimized pitch usage and the execution of his above-average changeup, helped refine his game against lefties. He held them to a .188/.260/.335 slash line last year.
Right-handed hitters, however, were a different story. His sweeper is his clear go-to pitch in those matchups—and it's a true 60-grade offering, with elite spin traits (2749 RPM) and two-plane tilt (-2.9" IVB, -13.0" HB), generating a 37.3% whiff rate in 2024. Despite the sweeper’s dominance, right-handed hitters still slugged .497 with an .853 OPS against him, largely due to his overreliance on the four-seam and cutter—two pitches that made up nearly 60% of his usage against righties but don’t profile well in those matchups.
Heading into 2025, Robberse has begun experimenting with a sinker in spring training, a pitch that could fill a much-needed gap in his arsenal. He previously lacked a hard pitch he could use to jam righties on the inner third, and an effective sinker would help keep hitters from sitting on pitches away.
With a deep arsenal, solid command, and plus spin traits, Robberse is a moldable arm with the capacity to continue evolving. His below-average fastball shape likely caps his ceiling, but the addition of a viable sinker will be vital for his next developmental step. If he can keep hitters off balance with the hard stuff and execute his pair of plus secondaries—sweeper vs. righties, changeup vs. lefties—there’s a clear pathway to him becoming a back-end starter. If not, shifting to a bullpen role where he can lean more heavily on the soft stuff—with the potential for a velocity bump—is another avenue for him becoming a big league contributor.
Future:
Robberse is an extremely adaptable arm with the pitchability and spin traits to manipulate shapes and sequence effectively as he climbs the ladder. While his lack of a quality fastball may ultimately limit his ceiling, his pair of above-average secondaries and his capacity to have a wide arsenal gives him a higher likelihood of sticking as a back-end starter than most would credit. With the Cardinals putting a greater emphasis on modern pitching development strategies, Robberse stands out as a potential breakout beneficiary.
