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40 in 40: Last chance to get on the Jonatan Clase hype train early

The switch hitting prospect with some pop has blink-and-you-miss-it level speed, but keep your eyes open, because they are one to watch.

Arkansas Travelers v Amarillo Sod Poodles Photo by John E. Moore III/Getty Images

It seems that no amount of measuring, no amount of observation, can accurately predict the hidden math of the subconscious. A brief period of minutes can be perceived as having felt like hours, with the physical fatigue to match. Alternatively, long hours can feel as but a moment, quickly fleeting. Either way, this fluid nature has us put a unique value to the currency of time; one not measured in numbers, but instead by our perceived relationship to events. Just a year or so ago it would be easy to say without error that most Seattle Mariners fans were not familiar with the name Jonatan Clase, or the player behind the name. Entering his age 22 season, the speedy outfielder with a small frame has been impressing his way through the minors, and now may be your last chance to get to know him before everyone does. All aboard the Jonatan Clase hype train!

The young outfielder hailing from Santo Domingo in the Dominican Republic first joined the Mariners organization when he signed as an international free agent in July of 2018. Blazing speed outweighed what was initially viewed as a too-small frame and led to his signing, but it didn’t take long for him to start turning heads as he showed some pop with the bat, and as Kate Preusser highlighted in a 2019 piece reflecting on his first year with the club, an exceptional work ethic. The pandemic sidelined his development some as it did so many others, but his ‘22 season in the minors saw him get back on track, with the efficiency of a bullet train. He spent the whole 2022 season in A ball with the Modesto Nuts and hung a slash of .267/.373/.463, a wRC+ of 117, and a monstrous 55 stolen bases. The largest area of concern was his strikeout rate of 26.7%, but balanced nicely with a walk rate of 13%. He performed well enough that on November 15, 2022, he was added to the 40-man roster to protect him from the Rule 5 Draft, and he made his Lookout Landing 40 in 40 debut last spring.

Clase’s season with the Nuts also earned him a promotion to start the 2023 season, and he began play with the High A Everett AquaSox. After twenty one games and a little over one hundred plate appearances he earned himself a promotion to AA with the Arkansas Travellers. Seven home runs, nine doubles, a triple, seventeen stolen bases, and a 203 wRC+ will do that. A high walk rate (17%) into that mix as well and he had a dazzling 1.154 OPS.

Across the 489 plate appearances he saw with the Travelers, he continued most of his positive trends, but also started showing the one major crack in his profile scouts had previously been worried about: contact. Clase has sneaky pop to his bat, and from both sides as a switch hitter, but he doesn’t have so much power to be a three true outcomes player and will need to rely on some level of contact skills for the pop to play to full effect. You can see this in his slash line at that level of .222/.331/.396, with an ISO of .174, a steep drop from the .368 he started the season with in High A. His strikeout rate also saw a modest rise to 28%, but was tempered with a pleasant walk rate of 13.1%, and the sixty-two stolen bases (in seventy-three attempts) he netted were good for the most in the Texas League.

Even with the elements of concern, it was still a season of resounding success for Clase. His seventy-nine stolen bases overall was good for third best in the minor leagues. He had five different games where he stole three bases. One with the AquaSox, and the remaining four at the higher level with the Travellers. His speed translated well to his outfield play as well, with him showing deftness at handling the outfield including center, and continued to see improvement of his routes and reading of the balls as they came off the bat.

If there were any Canadians on the Travelers last year, I’m sure it was often said “Clase is clutch, eh?”.

The pop from both sides of the plate was and will continue to be a fun watch.

And the power and speed play together beautifully, like in this play where he hit it to the wall in middle-left where the fielder quickly got to the ball, only for Clase to reach third and have it not even be close.

His 2022 season was the first time Jonatan Clase really started turning some heads, and in last year’s prospect rankings on this site, we had him at number thirteen in the Mariners system. His 2023 season continued that trend, and he gained momentum in his recognition both locally and abroad. Without spoiling too much he is certainly going up a tier on our site rankings this year, in part due to his increasing proximity to the league and the undeniably MLB quality of at least one skill. During the season last year he was recognized by being named to the 2023 All-Star Futures game, where he started as a leadoff hitter. After the season ended he was selected to play in LIDOM, and even appeared on national media lists of prospects to watch in that league. While his numbers were pretty flat in both arenas, his age and experience level quickly temper that from any worry. He was selected to compete because of the skills he’s demonstrated so far, skills already expected to play at the highest level, and the exposure to higher level pitching can serve to benefit him in the areas he needs to improve.

SiriusXM All-Star Futures Game Photo by Rob Tringali/MLB Photos via Getty Images

In fact, there is a current Seattle Mariners superstar, a speedy outfielder with pop to his bat, who once put up unimpressive winter ball numbers as well, only for it to matter none in their journey except as a learning opportunity. No, I’m not daring to suggest the Jonatan Clase is the next Julio, but I am suggesting there may be more in common than might seem on the surface, especially when you factor in their similar drive to be better. I’m not even the first person to make the comparison, as the power/speed/defense similarity was highlighted by Baseball Prospectus in their 2023 Annual. And even after his 2023 season with some concerns, he went up a rank in Baseball America’s top thirty for Seattle, having been placed number twelve in the system in 2023 and now at eleven in 2024.

At this point it is still fairly unclear exactly what the future holds for Jonatan Clase in regards to exactly the kind of player he can be. His tools enable him to have an exciting floor, the kind of player we have seen Seattle regularly embrace. A gamed pitch clock, a stolen base, a little bit of chaos… there are many ways for a player to make a name on the Mariners, if not league wide. Jonatan Clase, dare I say, has those skills now. The hustle, the heart, the ability to track a ball down in the outfield without looking lost, these in my mind guarantee that some day soon (well, not that soon) at the very least we will be seeing Clase on the roster in a Sam Haggerty, Dylan Moore like role. That is his floor. But if he can translate his work ethic and patience at the plate into improved contact rates, and I believe he will, the hype train may leave the station too fast for any of us to catch up.


Oh, I'm sorry, one more thing. It is a bit of a tradition around here that when we write about Jonatan Clase we also share a video highlighting a personal connection to this website. I am of course speaking about the video where Lookout Landing's own John Trupin challenged Jonatan Clase to a foot race, and even with a head start, Clase handily trumped, trounced, and torched Trupin. Sorry John, that's just what speed do.