White Sox Strengthen Rotation by Acquiring Three-Time All-Star Luis Castillo in Multi-Player Deal with Mariners
The Chicago White Sox have made one of their biggest moves of the season, completing a trade with the Seattle Mariners to acquire veteran right-handed pitcher Luis Castillo. The deal, finalized on Saturday night, signals Chicago’s commitment to strengthening its starting rotation despite Castillo’s struggles this year.
As part of the agreement, the Mariners receive relief pitcher Seranthony Dominguez, outfielder Nolan Jones, catching prospect Boston Smith, and conditional cash considerations. According to multiple reports, the White Sox will also assume the remainder of Castillo’s contract, which includes approximately $30 million guaranteed through the end of the 2027 season. Castillo is currently in the fourth year of the five-year, $108 million extension he signed with Seattle, and the contract also contains a $25 million vesting option for the 2028 campaign.
Although Castillo has not performed at his usual elite level in 2026, the White Sox are betting on his experience and track record. The 33-year-old enters Chicago with a 3-9 record and a 5.06 ERA across 20 appearances, including 17 starts. Over 99⅔ innings, he has struck out 86 batters while issuing 32 walks, making this statistically one of the toughest seasons of his career.
Despite those numbers, Castillo remains one of baseball’s most accomplished starting pitchers. Across nine Major League seasons with the Cincinnati Reds and Seattle Mariners, he has compiled an 87-93 career record with a 3.65 ERA. He has thrown more than 1,510 innings, recording 1,579 strikeouts while making 260 starts in 263 appearances.
Castillo’s accomplishments include three All-Star selections, earning honors with Cincinnati in 2019 and 2022 before representing Seattle in 2023. During that outstanding 2023 season, he also finished fifth in the American League Cy Young Award voting. His postseason résumé adds further value, as he owns a 2-3 playoff record with an impressive 2.25 ERA over six postseason appearances, experience that could prove invaluable for Chicago’s young pitching staff.
Seattle receives a proven bullpen arm in Seranthony Dominguez. The 31-year-old reliever posted a 4-3 record with 12 saves and a 4.10 ERA in 42 appearances during his first season with the White Sox. Across 37⅓ innings, Dominguez struck out 45 hitters while walking 23. Throughout his Major League career, which has included stints with the Philadelphia Phillies, Baltimore Orioles, Toronto Blue Jays, and White Sox, he has accumulated a 27-26 record, 52 saves, and a 3.57 ERA. He also contributed during Toronto’s postseason run last year, posting a 3.18 ERA in 12 playoff appearances.
The Mariners also add outfielder Nolan Jones, who has appeared in 349 Major League games with Cleveland and Colorado. Jones owns a career batting average of .247 with 30 home runs and 137 RBIs. Before the trade, he had been hitting .257 with 14 home runs and 59 RBIs across Triple-A affiliates for Cleveland and Chicago during the 2026 season. Jones originally entered professional baseball as Cleveland’s second-round selection in the 2016 MLB Draft and joined the White Sox earlier this summer.
Completing Seattle’s return is promising catcher Boston Smith. The 23-year-old prospect has impressed throughout Chicago’s minor league system in 2026, batting .291 with 22 home runs and 58 RBIs in 78 games while advancing from Single-A to Double-A. Smith was originally selected by the Washington Nationals in the sixth round of the 2025 MLB Draft before later joining the White Sox organization.
The trade represents a significant gamble for Chicago, but the White Sox are clearly hoping Castillo can rediscover the All-Star form that made him one of the American League’s premier starting pitchers. Meanwhile, Seattle adds immediate bullpen help and promising young talent as it continues to reshape its roster for the future.
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