White Sox move struggling Luis Castillo to bullpen

Castillo’s velocity issues suggest he’s been dealing with this for a spell, but it probably didn’t help decided to suddenly turn him into a reliever and use him on one day of a rest Tuesday. He still could potentially see some postseason time, but he ends the regular season 4-11 with a 5.85 ERA in 130 2/3 innings. He’s owed $22.75 million next year in the final season of a five-year contract.

Castillo gave up four hits, walked three and struck out two. He came in as the bulk pitcher, but lasted less than three innings. Castillo has a 10.00 ERA over his last five appearances. He has a 5.67 ERA this season. He’s lined up to face the Tigers at home next week.

Castillo also walked a pair of batters on the afternoon while striking out three. Jose Altuve tagged him for a two-run blast in the opening inning, then the Astros broke the game open with four more against him in the third. The 33-year-old right-hander got five whiffs on 78 offerings on the day, registering a CSW of only 22 percent. He’ll attempt to bounce back as he carries a 4-11 record, 5.57 ERA and a 1.46 WHIP into Wednesday’s matchup against the Pirates.

Castillo gave up eight hits, walked one and struck out three. He fell to 4-10 with the loss. Castillo has now allowed eight hits and four runs while failing to complete five innings in back-to-back starts since blanking the Reds for seven innings on August 12. Castillo has a 5.19 ERA. He’s lined up to face the Twins on the road next week as he tries to reverse his downward trend.

The White Sox would have liked more than this from Castillo with bulk guys going the next two days. The 33-year-old gave up a pair of homers and six additional hits, striking out just one in the process. He’ll try to do better this weekend against the Mets.

Castillo gave up one hit, walked two and struck out 10. He improved to 4-9 on the season with the win. Castillo gave the White Sox what they were looking for after he allowed five runs in his debut with the team last week. Castillo, who debuted with the Reds and spent six seasons in Cincinnati, dominated against his former team Wednesday. He’ll try to keep it going against the Cubs on the road next week.

Castillo struck out five and walked one, but that one preceded a two-run homer in the third. In the fourth, he allowed two singles and two doubles, though the lone hard-hit ball was a 95.2-mph groundball single from Masataka Yoshida. It really just wasn’t his night. Castillo, who had a 5.06 ERA for Seattle before being traded Saturday, probably isn’t going to be viable in mixed leagues in Chicago. He’s due to face the Reds next week.

Castillo is having the worst season of his professional career with a 5.06 ERA and 3-9 record over 20 appearances — 17 starts — and 99 1/3 innings. The 33-year-old right-hander has been much more effective in the past, however, and has pitched better after a dreadful start to his 2026 campaign. Still, this is not the Castillo of old, and he’s much closer to a streamer than someone fantasy managers need to have in their lineup. It’s fair to take a wait-and-see approach before believing in a rebound.

In exchange for Castillo, the Mariners will acquire right-handed reliever Seranthony Dominguez, outfielder Nolan Jones, and catcher/outfield prospect Boston Smith. The Whit Sox will also take on all of Castillo’s contract, which pays him 22.75 million the next two years with an option for 2028. The Mariners have long been rumored to explore trading a starting pitcher with Emerson Hancock and George Kirby’s name bandied about, but it’s Castillo who will be heading to Chicago. The right-hander is not the same hurler he was a few years ago when he was among the very best in the sport, but he’s a solid mid-rotation option for a team that has played well above expectations with an excellent chance of reaching October. He’s more streamer than fantasy stalwart, but perhaps the change of scenery helps Castillo find the form of the previous campaigns.

Passan adds that the sense is that Kirby is available and could be moved prior to Monday’s deadline. He also notes that Seattle has been listening to offer for Emerson Hancock and Luis Castillo. The Mariners have top prospect Kade Anderson knocking on the door of the majors and figure to move at least one, if not more, of their current rotation members. Kirby would net the largest return in any potential trade package, despite holding a pedestrian 3.98 ERA across 120 innings this season.