The Seattle Mariners traded Luis Castillo to the Chicago White Sox and are still open to moving George Kirby before Monday’s trade deadline, a sharp turn that could reshape the club’s pitching staff in the space of one day. Castillo goes with roughly $30 million still owed to him for the rest of this season and 2027, and the Mariners now have a clearer path to keep dealing if the market pushes them there.
That is why the Mlb Trade Deadline is the search term now: the Mariners have gone from selling one starter to leaving the door open on another, and the Chicago Cubs are already looking for multiple arms by Monday. Their list is wide enough to include Tarik Skubal, who has won the American League’s Cy Young Award for the past two seasons, plus Clay Holmes, Freddy Peralta, Adrian Morejon, Luke Weaver and Jeff Hoffman. Each name points to a different kind of upgrade, from a frontline starter to bullpen help.
The Castillo trade also answers the payroll question that sits behind so many deadline calls. By moving him, the Mariners cleared approximately $30 million in obligations, money that gives them more room to maneuver while they chase the stretch run. Before the deal, they already had six starters at the major-league level and Kade Anderson at Double-A, which is part of why the club can even entertain a move involving Kirby.
That possibility is the twist. For most of July, the Mariners indicated they would not trade Kirby, and he is controlled through 2028, so the change in posture is not small. Today’s shift, first reported by and the Seattle Times, suggests the club is weighing immediate flexibility against long-term rotation certainty. If Kirby goes, the Mariners would be signaling that the deadline is less about holding their ground than about using pitching depth as currency.
The Cubs’ pursuit is less settled, but it is already more crowded. Skubal remains on the board, Holmes is nearly ready to return from a fractured fibula, Peralta brings a strong connection to Craig Counsell from their Milwaukee Brewers days, and Morejon, Weaver and Hoffman all fit as bullpen adds. By Monday’s trade deadline, the real question is not whether Chicago wants to buy; it is how aggressively it will pay for the kind of pitching that changes October.
For the Mariners, the next move may be the harder one to read. Castillo is gone, the money is freer, and Kirby is no longer off-limits in the way he appeared to be for most of the month. That leaves one deadline hanging over the club now: whether the payroll relief from one trade becomes the setup for another before Monday arrives.
