On February 7, the Seattle Mariners designated Jhonathan Díaz for assignment. Díaz’s tenure with Seattle’s organization appeared to be over once he elected free agency after losing his roster spot to Casey Legumina.
However, Díaz made a career pivot and decided to re-sign with the Mariners on a minor-league contract Wednesday. Although he impressed last season in spring training, Díaz will be a non-roster invitee for 2025.
Díaz’s MLB career has been relatively brief until this point and he has failed to establish himself as a dominant bullpen arm in limited action. In four seasons with the Mariners and Los Angeles Angels, Díaz has only appeared in 16 games (45 innings) and has logged a 4.80 ERA and 1.733 WHIP.
Last season with the Mariners, Díaz appeared in five games and finished with a 0-1 record and a 4.66 ERA, which accumulated -0.1 bWAR. On June 11, his only start of the 2024 season, Díaz allowed nine hits while striking out four White Sox batters in 5 1/3 innings pitched.
One of the factors working against Díaz has been his low strikeout percentage as an MLB pitcher. Díaz is a soft-tossing southpaw with a fastball that averages between 89 and 91 mph. However, his repertoire is more suited for the minor leagues than MLB. Díaz has fanned only 15% of the batters he has faced in the bigs.
When Díaz pitched at Triple-A Tacoma, he was a solid pitcher who earned a call-up last season. At Tacoma, Diaz’s strikeout percentage hovered at 22%, while his walk percentage sat at 9.9%. Additionally, Diaz held a solid 54.1% ground ball rate at the Triple-A level. If Diaz can translate his success at Tacoma to Seattle, he can be a valuable asset to the Mariners pitching staff.
While the Mariners only have two left-handed pitchers on the current 40-man roster, it’s hard to imagine Díaz having a prolonged role this upcoming season. Given his career peripherals and after what he showed in 2024, Díaz is destined to spend most of the season in the minor leagues and serve as an emergency option at the big-league level.