Luis Castillo was a stalwart for the Mariners after they acquired him in a 2022 deadline deal with Cincinnati. Ross Turteltaub / Getty ImagesAug. 1, 2026 Updated 10:12 pm EDTThe Seattle Mariners on Saturday agreed to trade Luis Castillo to the Chicago White Sox for Seranthony Domínguez, Nolan Jones and Boston Smith, a league source told The Athletic on the condition of anonymity because the deal has not yet been announced.Castillo has been a stalwart for the Mariners since they acquired him in a 2022 deadline deal with Cincinnati. In the next three seasons, he went 36-29 with a 3.50 ERA, making at least 30 starts each year and earning the nickname “The Rock” for his consistency and reliability.But “The Rock” began to crumble last fall in the ALCS, when Castillo pitched just once in a seven-game loss to the Toronto Blue Jays, who knocked him out in the third inning of his loss in Game 4. This season has been the worst of his career.
Castillo has lasted six innings only five times in 20 appearances — a consequence, at times, of the Mariners’ rotation depth. With five other starters healthy, the Mariners have sometimes tried a “piggy-back” approach, which irked Castillo when he was removed from a start against the Athletics after four scoreless innings.Starting with that game, on May 25, through July 21, Castillo was fairly solid, with a 3.95 ERA. In his last start before the deadline, he gave up five runs and 11 hits in five innings.Castillo’s velocity is down from his later Reds seasons, when he averaged better than 97 mph. But his average fastball this season has measured 95.3 mph, which should be plenty hard enough to succeed with a sinker, slider and changeup.This story will be updated.
