The worst kept secret in baseball was that the Mariners may have been finally willing to move some of their starting pitching. Rumor turned into reality on Saturday night.
The worst kept secret in baseball was that the Mariners may have been finally willing to move some of their starting pitching. Rumor turned into reality on Saturday night.
The M's traded Luis Castillo to the Chicago White Sox in exchange for relief pitcher Seranthony Dominguez, outfielder Nolan Jones, and catching prospect Boston Smith.
The White Sox are expected to pay the remaining $30 million owed to Castillo after he signed an extension with the Mariners following his trade to Seattle in 2022.
On the surface, the trade covers needs for both sides. The Mariners needed outfield help and more especially a high-leverage bullpen arm.
Jones was once a highly touted prospect in the Cleveland farm system at outfield, Dominguez has sort of served in a closing role for the White Sox with 12 saves this season. He most recently pitched Thursday in the 11th inning getting the win for Chicago over the New York Yankees
Smith was in the 2025 draft and is already playing at the AA level, similar to the catcher the Mariners picked in the 2025 draft Luke Stevenson.
Of course, even if the trade makes sense on paper, it's an emotional one for Mariners fans.
"The Rock" as he was known, Luis was the Opening Day starter and anchor of the rotation in 2023 and 2024 for the M's not to mention the massive impact he had after coming over during the 2022 trade deadline.
A trade that, if you look at "most lopsided trades" articles, is often cited as a huge win for the Mariners.
Indeed, Castillo will be missed for his play and personality.
“His arrival, and subsequent performance in 2022 set the tone for what has been a fantastic run as a Mariner. We all appreciate everything he has done in Seattle and wish him continued success in all he does," said Mariners President of Baseball Operations Jerry Dipoto in a statement.
But there was a growing problem -- a good one -- in too many starting pitchers.
The Mariners tried to employ the "piggyback" method but that caused some disgruntling among fans and players alike.
The reality is a 6-man rotation during a normal schedule with off days can be cumbersome, not to mention the Mariners have two guys ready to go in the minors in Kade Anderson and Ryan Sloan.
Couple all that, with deficiencies of their own with a recent slide and a deal had to be made with one of the six starters.
While I don't think this is lopsided for either side, I wouldn't be shocked if Castillo surges with the White Sox. He'll be one of the lead guys in that rotation expected to mentor a young but talented group.
The Mariners desperately needed another arm in the bullpen and get a high leverage one at that. It should alleviate some of these late-inning losing of leads we've seen this summer.
Dominguez provides that veteran depth for the late innings. Even if he may be remembered by Mariners for another reason, giving up the epic grand slam by Eugenio Suarez in Game 5 of the ALCS with the Blue Jays last year.
Jones and Smith have potential to be sure, so there's upside even beyond the immediate return.
The only question now is, do the Mariners have more moves up their sleeve?
