Another totally unique Mariners pitching prospect surging with super slow fastball

Fastball velocity is sort of the Seattle Mariners' whole thing. They ranked second in the league with an average heater of 95.2 mph this season, which raises the question of what use they would have for a guy like Tyler Cleveland, whose fastball sits in the mid 80s.

Well, here's a hint: That fastball and Cleveland's other offerings come from an angle unlike any other that today's professional hitters are used to.

We first wrote about Cleveland in June, when the right-hander was merely a curiosity on account of his submarine-style delivery — he's called the "SubMariner," because of course he is — with an extremely wide release point. Several months later, he now looks like a proper prospect.

A super slow fastball is not hindering Tyler Cleveland's unique rise toward the majors

The 26-year-old Cleveland was named to the Northwest League All-Star team in September, and it was around then that he got promoted from High-A Everett to Double-A Arkansas. He ultimately made 41 appearances throughout the MiLB season and allowed only five earned runs in 51.2 innings, good for a 0.87 ERA.

Cleveland has more recently been pitching in the Arizona Fall League, where he caught the attention of Jonathan Mayo of MLB.com for a feature story. In it, Cleveland explained how he was a traditional over-the-top pitcher in high school before dropping down during his college career at Central Arkansas.

"I ran with it and just dropped down," Cleveland told Mayo. "It wasn't naturally where I'm at now. By the end of it, I didn't watch any video, I just continued to try to drop down and by the end of it, I kind of ended up where I am now."

You really have to see Cleveland's delivery to believe it. He sets up on the first base side of the rubber, bends in half and releases the ball from a sidearm motion as far to the third base side of the infield as he possibly can. By the time the ball leaves his hand, it's pretty much starting toward the plate from the outside edge of the right-handed batter's box.

From a horizontal perspective, the most extreme right-handed release point in the majors this season belonged to Matt Bowman of the Baltimore Orioles. Yet even he doesn't quite work as a comp for Cleveland, who is three inches taller and is more of a proper side-armer. Cleveland is more like Tyler Rogers, who has carved out a nice niche as an effective submariner despite his low-to-mid 80s velocity.

It's such an unusual profile that you can hardly blame MLB Pipeline for only rating Cleveland as the Mariners' No. 30 prospect. Yet you can at least imagine a future in which he is a right-on-right specialist, if not more based on his splits. He held righties to a .319 OPS this season, but lefties didn't do much better to the tune of a .430 OPS.

After the success he had in 2025, Cleveland is a candidate for a quick promotion to Triple-A Tacoma at the outset of the 2026 season. That would put him a step away from Seattle, and you just know the Mariners are going to need relief help at some point next season.

If they call on Cleveland, he'll have a chance to become sort of a welcome outcast in the bullpen. As long as the outs are there, it won't matter that he's about as far from typical as a Mariners pitcher can get.