Mariners add Seranthony Dominguez in Castillo trade

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.

Taylor took over with the tying run on third and one out in the eighth, putting him in prime position for a cheap blown save. However, he got out of the jam by striking out Shea Langeliers and getting Jonah Heim to ground out. He then walked one in a scoreless ninth that was made easier because the A’s took out decent left-handed hitters for weaker right-handed bats while trying to score off Sean Newcomb in the seventh. Seranthony Domínguez again went unused today, and Taylor is the pretty clear favorite for saves in Chicago, even if he’ll occasionally work earlier in games sometimes.

The scoreless inning is good, but it sure doesn’t seem like Domínguez is going to be in line for saves again any time soon. Since blowing back-to-back save chances on June 21-22, he’s been limited to just three appearances, two coming in the sixth and one in the seventh. Grant Taylor is the White Sox reliever worth rostering at the moment.

It was a tough break for Taylor, who was back on the mound today after throwing 50 pitches between Sunday and Monday. Seranthony Domínguez, on the other hand, had a second straight day off after throwing 49 pitches and taking blown saves in both of those games. Taylor seems likely to factor into more save chances if Domínguez continues to struggle, but he’s also having issues at the moment; he’s given up eight runs — six earned — over 6 2/3 innings in his last five appearances.

Domínguez couldn’t protect a one-run lead in the ninth inning for the second consecutive day. After blowing the save in Detroit on Sunday, he came home and blew another save in Chicago on Monday. Domínguez’ grip on the closer job would seem tenuous at best, though Grant Taylor also gave up runs in the last two games and was even charged with a blown save of his own on Monday. Still, the White Sox moved into first place with the win. Whether it’s Taylor or someone else, a closer change could make sense for a team with postseason aspirations like the White Sox.

Domínguez entered with a one-run lead but couldn’t slam the door. It’s a disappointing result given Grant Taylor allowed a homer in the eighth inning, so Domínguez might’ve put more distance between himself and Taylor in the battle for ninth-inning chances. Domínguez will likely remain the go-to option considering Taylor has been shaky lately, but this is a closer situation to keep tabs on throughout the summer.

It was far from a clean outing for Dominguez, which has been more common than not over the first half of the season for the 31-year-old. He issued a pair of walks, and he allowed an RBI double by Alex Freeland to cut the Dodgers’ lead to 6-4. He was able to keep Los Angeles off the board from that point on, however, and he was able to procure his 12th save of 2026.

Some interesting bullpen usage for the White Sox today, as Grant Taylor came in during the sixth with a 2-1 and escaped a jam for Anthony Kay. He then worked a scoreless seventh. It was a 4-1 game when Domínguez entered, but it doesn’t seem likely that he would have been asked for a two-inning save after working a scoreless ninth in a tie game Friday. Perhaps Bryan Hudson would have been in line for a save, but it proved moot after the White Sox made it a 7-1 game in line for the ninth. Trevor Richards finished up at that point. Hudson could still get a save Sunday, since we assume both Domínguez and Taylor will be unavailable.

It’s Domínguez’s first save since May 13. He blew a chance four days later and had pitched just once in the last week, getting some work in with a scoreless inning in Sunday’s loss to the Giants. Grant Taylor is definitely a threat to Domínguez in the White Sox pen, but ideally, Domínguez would do well enough to keep the job and leave the White Sox free to use Taylor in tie games and for two innings at a time on occasion. Domínguez thus far is 11-for-14, with the White Sox going 1-2 in his three blown saves. He and Taylor, who pitched a scoreless seventh today, might both need Tuesday off after working the last two days, possibly creating a save chance for Bryan Hudson. Or perhaps the White Sox would risk using Domínguez for a third straight day.

Domínguez walked Alex Bregman to begin the inning before striking out Ian Happ. Seiya Suzuki then reached on an error before Michael Conforto connected for a three-run, game-tying jack. Domínguez signed a two-year, $20 million deal with the White Sox this past offseason. That’s closer money, but he simply hasn’t pitched as one of the best relievers in this bullpen. Grant Taylor has the skills to usurp the job if Chicago is willing to move on from his multi-inning role. Domínguez has earned 10 saves so far in 2026, but his 2.4 HR/9 is the sixth-highest among qualified relievers.