Mariners Acquire RHP Cooper Criswell from Mets in Exchange for Cash Considerations
SEATTLE – Seattle Mariners Executive Vice President & General Manager of Baseball Operations Justin Hollander announced today the Mariners have acquired RHP Cooper Criswell from the New York Mets in exchange for cash considerations. In a corresponding move, LHP Jhonathan Díaz was designated for assignment.
The Mariners 40-man roster remains full at 40 players.
Criswell, 29, appeared in 7 Major League games (1 start) in 2025 with the Boston Red Sox, going 1-0 with a 3.57 ERA (7 ER, 17.2 IP). He was claimed off waivers by the New York Mets from the Red Sox on December 5, 2025 and designated for assignment by the Mets on January 21, 2026.
Criswell was originally drafted by the Los Angeles Angels in the 13th round of the 2018 MLB First-Year Player Draft. He has appeared in parts of 5 Major League seasons with the Angels (2021), Rays (2022-23) and Red Sox (2024-25). The 6-foot-6 righty is 8-7 with a 4.48 ERA (77 ER, 154.2 IP) in 45 MLB games (21 starts).
Díaz, 29, appeared in 1 game with the Mariners in 2025. He appeared in 27 games (26 starts) with Triple-A Tacoma, leading the Pacific Coast League with a 4.15 ERA (64 ER, 138.2 IP). Over two seasons with the Mariners, Díaz appeared in 6 games, going 0-1 with a 4.09 ERA (5 ER, 11.0 IP).
Díaz has appeared in parts of 5 Major League seasons with the Angels (2021-23) and Mariners (2024-25), making a combined 17 appearances (7 starts). The Valencia, Venezuela native has also appeared in parts of 10 minor league seasons in the Red Sox (2014-19), Angels (2021-23) and Mariners (2024-25) organizations, going 73-47 with a 3.81 ERA (410 ER, 967.1 IP), 316 walks and 913 strikeouts in 213 games (176 starts). He was originally signed by the Red Sox as an international free agent on July 2, 2013.