Joining our 2026 prospect rankings at #19 overall, Beilenson is our first of a few pure relief prospects we’ll see on the back half of our rankings this year. Something that’s been atypical in recent seasons, with the large exodus of prospect talent over the past year and change, some of these higher floor relief types are creeping their way into the top twenty due to a lack of impact towards the end of this system. They’re probably not going to be the sexiest names that most people know, but there’s value in predictability, and that’s precisely what these kinds of arms provide.
Taken in the fifth round of the 2024 draft as a senior sign out of Duke, Beilenson was one of many college relievers the Mariners took in order to afford signing stud right-hander Ryan Sloan away from his college commitment in the second round. He was, however, arguably the top collegiate reliever that season and would have been a popular target for any team in a similar situation financially. Not a top prospect, but far from an afterthought.
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On the bump, Beilenson features a legitimate three pitch mix that’s consistently performed well during his time in the Seattle organization. His fastball lives in the mid 90’s and is a capable offering, however he truly makes his money with a parachuting changeup and tight slider. None of his offerings are truly a “wipeout” offering per se, but the combination of the three allows him to get enough whiff to survive in the modern baseball climate. Plus, he’s got premium command of his entire arsenal, frequently working ahead in counts and rarely giving in if he falls behind. Perhaps not a dynamic strikeout artist, but a really solid arm to have in your system.
Over the span of his 2025 season, Beilenson pitched in two disparate offensive environments for two halves of the season: Everett’s Funko Field and Arkansas’ DSP. Interestingly, those aforementioned homer problems crept up at a roughly equivalent rate regardless of level, perhaps indicating his homer luck was a bit wacky over the course of last season. The underlying stats would agree with that sentiment, as despite his 4.02 ERA, Beilenson had a 2.78 xFIP (FIP that has essentially been “homerun luck” adjusted) on the year, an excellent mark that paints a brighter picture of his true ability on the mound.
Beilenson is pushing to carve out a big league future by inducing a ton of ground balls (48.8 GB%) and commanding the zone. It’s probably a middle-innings type of ceiling that doesn’t have any true outlier trait, but the numbers are interesting enough to warrant his inclusion towards the end of our rankings. Having turned 26 a few months ago, Beilenson is old for a prospect yet to debut in AAA, but with little pressure to rush him to the majors, he’ll have plenty of time to acclimate to AAA and prove he can be a viable big league depth arm for the 2026 season.
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