The Seattle Mariners made the opening salvo of their trade deadline on Saturday night by dealing veteran right-hander Luis Castillo to the Chicago White Sox for a package of reliever Seranthony Dominguez, outfielder Nolan Jones and prospect Boston Smith.

The Mariners are shedding all of Castillo's salary while absorbing all of Dominguez's. In essence, the Mariners are saving about $15 million in 2027, plus some money for the rest of 2026. Of course, some of those savings will go to raises for current players through arbitration, as long as the arbitration still exists in the new labor agreement.

Beyond that, there are many, many tentacles to this deal. Let's go a little deeper:

Dominguez, 31, is not a perfect pitcher. He's 4-3 with a 3.99 ERA, but he does miss bats, having struck out 47 batters in 38.1 innings. He served as a closing option for the White Sox, but he will not be in that role with the Mariners.

In the absence of Matt Brash and Carlos Vargas, the M's bullpen has really only been operating with four leverage arms (Munoz, Eduard Bazardo, Jose Ferrer and Gabe Speier). Dominguez will add to that group, and he may end up supplanting Bazardo in his leverage role, forcing him into a pivot role.

There is still a chance that the Mariners could trade George Kirby or Emerson Hancock, which would complicate this, but for now, it seems like the six-man rotation is done. Seattle has operated with a six-man rotation for the last month and change but this would seem to put an end to that, giving the Mariners just five starters and a full eight-man bullpen.

Assuming the Mariners keep their current group of five starters in tact, this would mean that Anderson is the next in line to help the rotation should someone get injured.

The team may prefer to keep Anderson as a bullpen option for later in the season, but if they need an additional starter, it could be his turn. Of course, veterans like Jhonathan Diaz and Casey Lawrence could be called upon as well.

Is there any chance that the Mariners could keep the six-man rotation and insert Anderson into it in place of Castillo? It seems unlikely, especially because of service time considerations, but there's at least a chance, and the six-man rotation would help keep Anderson on proper rest in his first professional season.

Well, with nearly $15 million more to spend in 2027, there are curiosities as to what the Mariners will do with that money. Of course, all of this depends on the labor situation over the offseason. Will the M's even be allowed to fully benefit from these savings, or will there be a salary cap that forces them into a spending range?

The Mariners will finish out a series with the Minnesota Twins on Sunday at 1:10 p.m. PT. Right-hander Taj Bradley will pitch for Minnesota while George Kirby is scheduled to pitch for Seattle, as long as he's still on the roster.

The Mariners are 54-58 and two games back of the third and final wild card spot. They are three games back in the American League West.