The Chicago White Sox entered the trade deadline weekend as the AL Central leaders. While they are in the top ten in MLB with a 4.03 ERA this season, it did not stop them from strengthening their rotation. Despite having a deep pitching staff, the front office went for one of the most eye-catching moves involving four players. 

“BREAKING: The Chicago White Sox are acquiring right-hander Luis Castillo in a trade with the Seattle Mariners for reliever Seranthony Domínguez, outfielder Nolan Jones and catching prospect Boston Smith, sources tell ESPN,” Jeff Passan tweeted August 1. 

Luis Castillo signed a five-year, $108 million contract with the Seattle Mariners in September 2022. The White Sox will take over approximately $30 million of his salary, which includes the remainder of this year and $22.75 million for 2027. Castillo also has a $25M vesting option for 2028 if he pitches 180 innings in 2027. In return, Chicago is sending a major league pitcher and two minor leaguers to the Mariners. 

The White Sox were the only team in the AL Central with an above .500 record as of 11 p.m. EST Saturday night. They have a solid rotation with players like Sean Burke, Erick Fedde and Noah Schultz. Burke has emerged as an ace for Chicago with a 3.04 ERA and 140 SOs. Fedde (4.13 ERA) and Schultz (6.15 ERA) have tried their best to help the White Sox remain atop the division. 

But Castillo has a 5.06 ERA with a 3-9 record in 2026. The ten-season veteran has the worst numbers in his career. It’s not his current numbers but the experience as a three-time MLB All-Star that made the White Sox rope him in. He has multiple postseason appearances, and the team wants someone of his caliber to help them in October. 

Meanwhile, the Mariners received three players in this trade.

Seranthony Domínguez has a 4.10 ERA with 12 saves in 42 games this season. Although he has one of the worst numbers in his career, his postseason experience from the last four years will surely come in handy for the Mariners. 

Nolan Jones has spent four seasons shared between the Cleveland Guardians and Colorado Rockies in MLB. But poor performance saw him stuck in Triple-A this year. The outfielder currently has a .255 batting average and .804 OPS. Meanwhile, Boston Smith is batting at .291 with a 1.039 OPS. The catcher-outfielder was picked by the Washington Nationals in the sixth round of the 2025 Draft. He’s a No. 15 prospect in Chicago. 

Trade buzz surrounded Luis Castillo almost since the beginning of this season. Back in April, he was heavily involved in a rumored move to the New York Yankees. But it didn’t ultimately happen, and he remained in Seattle.

Now, he will join the White Sox to play a role in their attempt to end the two-decade-long World Series drought. But Chicago isn’t done adding pieces to the roster. Some reports suggest that they might add more pitching and catching help before the window closes.