Mariners to promote top OF prospect Jonatan Clase

The Mariners will be calling up outfield prospect Jonatan Clase, according to ESPN’s Kiley McDaniel. It seems like Clase will replace Dominic Canzone on the active roster, as Canzone suffered a left AC joint sprain in Sunday’s game and will surely be placed on the 10-day injured list. No further roster move will need to be made since Clase is already on Seattle’s 40-man.

Clase’s first appearance in a game will mark his official MLB debut, and the highlight of a pro career that began as an international signing in 2018. Over 1483 plate appearances in the minors, Clase has hit .263/.376/.457 with 39 homers and 183 stolen bases (out of 221 attempts). Those numbers include a .308/.404/.641 slash line in 47 PA for Triple-A Tacoma this season, which marked Clase’s first taste of Triple-A ball.

The combination of this hot start and Canzone’s injury have now punched Clase’s ticket to the Show, though questions remain about his all-around readiness. Baseball America and MLB Pipeline each rank Clase as the 10th-best prospect in the Mariners’ farm system based on his incredible 70-grade speed and impressive overall set of tools, but as BA’s scouting report notes, “he is an aggressive and energetic player, who alternately excites and frustrates.”

Clase (who turns 22 next month) has struck out in 25.55% of his career minor league plate appearances, making him a bit of a three-true-outcomes style of player given that he draws a fair share of walks and has some good raw power. At only 5-foot-9 and 150 pounds, Clase doesn’t fit the usual physical model for a power hitter, so if the power doesn’t translate against Major League pitching, Clase will need to improve his contact to better maximize his speed. 

As MLB Pipeline’s report puts it, “maintaining a sound approach and not selling out for power and getting away from his best abilities will also be vital.”

Clase became a switch-hitter in 2022 and his career splits are generally pretty even, though his numbers are a lot better as a left-handed batter in his small sample of Triple-A at-bats. This could indicate that he’ll slide into Canzone’s role as the left-handed hitting side of a left field platoon with righty-swinging Dylan Moore. 

Clase doesn’t have a great throwing arm so he has played only left and center field, and his glovework is considered solid enough to handle some center at the big league level.