White Sox acquire Luis Castillo from Mariners in trade

The Chicago White Sox are acquiring right-handed pitcher Luis Castillo from the Seattle Mariners for reliever Seranthony Dominguez, outfielder Nolan Jones and catching prospect Boston Smith, the team announced Saturday.

Castillo, 33, is 3-9 with a 5.06 ERA in 20 appearances (17 starts) this season, giving up 107 hits in 99⅔ innings. He has a career 3.65 ERA over 10 seasons, though he is having the worst year of his career.

He is in the fourth year of a five-year, $108 million contract, which has a vesting option for 2028.

White Sox general manager Chris Getz highlighted Castillo as a reliable option to take up innings, something the team has struggled to get from its rotation this season.

“This was an opportunity to bring in a starting pitcher that we’re really excited about. Someone that can help lead this young pitching staff, not only cover innings, but has experience pitching in the playoffs,” Getz said Sunday.

Dominguez, 31, was 4-3 with a 3.99 ERA and 12 saves over 43 appearances for Chicago. He is signed through 2027 after inking a two-year, $20 million contract with the White Sox before this season. He offsets the large salary the team is taking on in acquiring Castillo.

Jones, 28, has been at Triple-A all season after being in Cleveland‘s and Colorado‘s organizations while Smith, 23, the 15th-ranked prospect for Chicago, was hitting .306 at Double-A in 22 games.

If the White Sox can get the best out of Castillo, he will slot in the middle of a rotation that has recently featured Anthony Kay, Erick Fedde and rookie Noah Schultz. Fedde and Schultz had good outings this weekend against the first-place Tampa Bay Rays, but the latter pitcher is likely to be moved out of the rotation. The White Sox used an opener for him in a 1-0 loss Saturday.

Castillo’s numbers have been worse in 2026 while playing in pitcher-friendly T-Mobile Park, though he is just a year removed from posting a 3.54 ERA over 180 innings. He also has postseason experience, something none of Chicago’s other starters possess.

The White Sox are still working on acquiring more talent before Monday’s trade deadline. Another starter and/or reliever could be a possibility. Replenishing their catching depth is another possibility with starter Kyle Teel out for most of what’s left of the regular season.

“It’s still on our radar. It is. We’re staying in contact with clubs,” Getz said of the White Sox’s catching search. “And it seems that there are a handful of clubs that are out there looking for catching. So that’s made the market maybe move a little bit slower than you would like. So we’re going to continue to monitor the catching market. I anticipate we do something.”