SEATTLE — Seattle Mariners executive vice president and general manager of baseball operations Justin Hollander announced today that the club has acquired right-handed pitcher Cooper Criswell from the New York Mets in exchange for cash. As a corresponding move, Venezuelan left-hander Jhonathan Díaz was designated for assignment.
Criswell, 29, appeared in seven major league games (one start) in 2025 with the Boston Red Sox, going 1-0 with a 3.57 ERA (7 earned runs in 17.2 innings). He was claimed off waivers by the Mets from Boston on December 5, 2025 and later designated for assignment by New York on January 21, 2026.
Criswell was originally selected by the Los Angeles Angels in the 13th round of the 2018 Amateur Draft. He has seen action in parts of five seasons in the Majors with the Angels (2021), Rays (2022-23) and Red Sox (2024-25). The 6-foot-6 right-hander is 8-7 with a 4.48 earned run average (77 earned runs in 154.2 innings) in 45 MLB games, including 21 as a starter.
Díaz, 29, appeared in one game with the Mariners in 2025. Additionally, he pitched in 27 games (26 starts) with Triple-A Tacoma, leading the Pacific Coast League with a 4.15 ERA (64 earned runs in 138.2 innings). In two seasons with Seattle, Díaz pitched in six games, going 0-1 with a 4.09 ERA (five earned runs in 11.0 innings).
Díaz has participated in parts of five seasons in the Major Leagues with the Angels (2021-23) and the Mariners (2024-25), with a total of 17 appearances (seven starts). The Valencia native has also pitched in parts of 10 minor league seasons within the Red Sox (2014-19), Angels (2021-23) and Mariners (2024-25) organizations, with a 73-47 record, 3.81 ERA (410 earned runs in 967.1 innings), 316 walks and 913 strikeouts in 213 games (176 openings). He was originally signed by the Red Sox as an international free agent on July 2, 2013.
