White Sox add veteran RHP Luis Castillo, send 3 players to Mariners

Field Level Media|published: Sun 2nd August, 24:37 2026

Jul 28, 2026; Los Angeles, California, USA; Seattle Mariners pitcher Luis Castillo (58) delivers a pitch during the second inning against the Los Angeles Dodgers at Dodger Stadium. Mandatory Credit: William Liang-Imagn Images

The Chicago White Sox bolstered their pitching staff by acquiring three-time All-Star right-hander Luis Castillo from the Seattle Mariners on Saturday night.

The Mariners receive right-handed reliever Seranthony Dominguez, outfielder Nolan Jones, Chicago's No. 15 prospect in minor league catcher Boston Smith and conditional cash considerations. The White Sox will pay the remainder of Castillo's salary, according to multiple reports, which is about $30 million guaranteed from now through the 2027 season.

Castillo is in the fourth year of a five-year, $108 million contract with a $25 million vesting option for 2028. He is having his worst season at 3-9 with a 5.06 ERA in 20 games (17 starts). The 33-year-old has recorded 32 walks and 86 strikeouts in 99 2/3 innings.

For his career, Castillo is 87-93 with a 3.65 ERA, 485 walks and 1,579 strikeouts in 1,510 1/3 innings over 263 regular-season games (260 starts) for the Cincinnati Reds (2017-22) and Mariners (2022-26).

He was selected to the All-Star Game with the Reds (2019, 2022) and the Mariners (2023) -- finishing fifth in the American League Cy Young Award voting that season.

Castillo is 2-3 with a 2.25 ERA in 28 innings over six postseason games (five starts) -- experience lacking in Chicago's other starters.

Dominguez, 31, is 4-3 with 12 saves, a 4.10 ERA, 23 walks and 45 strikeouts in 37 1/3 innings over 42 relief appearances in his first season with the White Sox.

He has a career record of 27-26 with 52 saves, a 3.57 ERA in 343 1/3 innings over 364 relief appearances. He has pitched for the Philadelphia Phillies (2018-19, 2021-24), Baltimore Orioles (2024-25), Toronto Blue Jays (2025) and White Sox. He went 2-0 with a 3.18 ERA in 12 appearances during the Blue Jays' playoff run last season.

Jones, 28, is batting .247 with 30 home runs and 137 RBIs in 349 games with Cleveland (2022, 2025) and the Colorado Rockies (2023-24). Jones was batting a combined .257 with 14 homers and 59 RBIs in 90 games with the Guardians' and White Sox's Triple-A affiliates this year.

Cleveland selected Jones in the second round of the 2016 MLB Draft. He was traded to the White Sox for $250,000 in bonus pool money and cash considerations on June 11.

Smith, 23, has played 78 games in the White Sox's minor league system from Single-A to High-A to Double-A this season and batted .291 with 22 homers and 58 RBIs.

The Washington Nationals picked Smith in the sixth round of the 2025 draft out of Wright State.

--Field Level Media

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