White Sox deadline trade with Mariners already looks promising after Luis Castillo's gem

The White Sox biggest move of the 2026 trade deadline was a bit controversial. Chicago, in desperate need of starting pitchers that could eat innings, dealt RHP Seranthony Dominguez, OF Nolan Jones, and catching prospect Boston Smith to Seattle in exchange for right-hander Luis Castillo. Castillo, a three-time All-Star, has a history of success in the big leagues but is having the worst season of his career. Those who were critical believed it was too much of a risk to take on Castillo’s hefty $22.5 million salary and hope for a bounce back. 

Through two starts, Castillo has shown the type of upside the White Sox hoped to get when they made the deal. After an outing against Boston that saw Castillo deal with some brutal batted ball luck and face the hottest team in the league, he got a chance to face his former team, the Cincinnati Reds, on Wednesday. Castillo fired seven scoreless innings, allowing just two singles and striking out ten. He racked up 22 whiffs and threw 104 pitches, providing both the length and quality of innings the White Sox needed. 

Castillo's increased chanegup usage will be the key to his success

When looking at Castillo’s pitch grades, his changeup continuously stands out as his strongest offering. However, over the past two seasons, Castillo has decreased his changeup usage significantly. He’s always primarily used the pitch against lefties, but during his 2023 and 2024 seasons, he was throwing the pitch around 25% of the time, and that has decreased to around 18% over the past two years. His pitches haven’t lost much life this season, so his struggles can most likely be explained by the decreased usage of his best pitch and poor location of his other offerings. Those are both trends that Castillo started to break on Wednesday night. 

In seven innings, Castillo threw 57 pitches to left-handed hitters. Of those 57, 20 were changeups. That’s 35% of his offerings to lefties, a stark increase from his 19% mark for the season. It seemed like the plan for Castillo was to use his best pitch more, and he located it well on Wednesday. Having success with his changeup will allow him to keep hitters off-balance with his other pitches and make his entire arsenal more effective. 

I’m not suggesting that every outing for Castillo will mirror Wednesday’s gem. It was only the second time since 2023 that Castillo has struck out ten hitters in a game, and that includes two very strong seasons, so it was more of an outlier than anything. But there are themes we can take away that give the White Sox a blueprint for how to get Castillo back to his All-Star form. 

Castillo is currently slated to take the ball next on Monday against the Cubs, who have been one of the best offenses in baseball in recent weeks. It’ll be a tough challenge for Castillo, a fly ball pitcher, to excel at a hitter-friendly Wrigley Field against a tough Cubs offense, but locating like he did Wednesday night will certainly help. 

If Castillo can put together more outings like he did on Wednesday, not too many people will be questioning the trade from the White Sox perspective, and he’ll be an important part of the rotation for the remainder of 2026 and beyond.

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