When Luis Castillo was acquired by the Chicago White Sox from the Seattle Mariners , the hope was that Chicago would be able to fix the pitcher's awful season. Unfortunately, he's regressed even further.
At the trade deadline, Castillo was traded to Chicago for prospect Boston Smith, minor leaguer Nolan Jones , and major league reliever Seranthony Dominguez . He was the only starter Chicago acquired at the deadline. For a team that has had issues practically all season with starting pitching, this came as a surprise to many. Castillo has done poorly, to say the least, with the White Sox, and Smith has continued his dominance in Seattle's farm system.
This trade just keeps getting worse for the White Sox , as they have now moved Castillo to the bullpen amid his struggles, according to manager Will Venable via ESPN's Jesse Rogers. David Sandlin will take the bulk of the work for the White Sox in Castillo's place.
Sep 3, 2026; Houston, Texas, USA; Chicago White Sox starting pitcher Luis Castillo (58) has a pitchers mound visit against the Houston Astros in the third inning at Daikin Park. Mandatory Credit: Thomas Shea-Imagn Images | IMAGN IMAGES via Reuters Connect
In seven games (six starts) since the trade, Luis Castillo has been awful. He owns a 7.76 ERA in that time, pitching just 29 innings and striking out just 25, with a .328 opponent batting average. Excluding one great start against his former team, the Cincinnati Reds , Castillo has failed to reach five innings in each appearance. Now, he will be in the bullpen for the remainder of the regular season.
It's unclear what his postseason role will be with Chicago, should the White Sox finish strong and make the playoffs. However, Chicago has realized that they can't have Castillo pitching in important moments.
This just makes the trade look even more foolish after what the White Sox gave up for the former three-time All-Star. Smith is now the Mariners' No. 13 prospect after not appearing on the White Sox's top-30 before the 2026 season. His meteoric rise alone should make this a tough pill to swallow for GM Chris Getz.
This was Smith's first professional season. He started in Low-A and worked his way up to Double-A, dominating at every stop. He has slashed .274/.424/.566 with 31 home runs and 11 stolen bases in 112 games between the Chicago and Seattle organizations.
While the other pieces of the trade in Jones and Dominguez have made little to no impact, Smith could very well make it to the majors as soon as next season.
With the White Sox fading down the stretch due to their lack of starting pitching depth and Castillo's awful performances when he has been on the mound, this trade deadline move (and lack of others) could very well affect the White Sox's postseason chances as we conclude the regular season.
This article was originally published on www.si.com/mlb/whitesox/onsi as White Sox' Luis Castillo Trade Looks Even Worse After Latest Will Venable Decision .
