Mariners trade Luis Castillo to White Sox for reliever and two prospects

Seattle traded starting pitcher Luis Castillo to the Chicago White Sox on Saturday night, receiving reliever Seranthony Domínguez and two minor-league players in return. The White Sox, who lead the AL Central, added Castillo to bolster a rotation that has already been strong this season.

The Mariners, who have carried six starters in their rotation, had been expected to move pitchers before the trade deadline. Castillo, the highest-paid and lowest-performing of Seattle’s starters, had struggled this year, posting a 5.00 ERA and failing to pitch beyond six innings in most of his 20 appearances.

In addition to Domínguez, Chicago sent outfielder Nolan Jones and catching prospect Boston Smith to Seattle. Jones, a former top prospect in the Guardians system, has posted a .257/.362/.445 slash line in Triple-A this season. Smith, a 23-year-old, posted a .291/.448/.589 line in Double-A and was hitting .306 with eight home runs in 22 games before the trade.

Domínguez, who signed a two-year, $20 million contract with Chicago in January, has a 4.10 ERA in 42 appearances this season and has been used in high-leverage situations.

Seattle also retains a deep pool of young arms, including top prospect Kade Anderson, the third overall pick in last year’s draft, who is pitching at Double-A with a 1.20 ERA and a .408 opponent OPS.