Despite many rumors over the years, the Mariners have long resisted the idea of a trade from their strong rotation. That trend looks set to continue at this year’s deadline, as Adam Jude of the Seattle Times writes that the M’s “have given no indication that they are willing to move any of their top five pitchers this summer.” That being said, Jude speculates that “July has come…Luis CastilloThe word statistics will resurface in trade discussions.”
Caveat underscores the fact that Castillo is no longer considered one of the Mariners’ top rotation options. This was evident when Castillo was used twice as a piggyback starter in the backfield Bryce Miller and Miller returned for the season opener from the 15-day injured list. Emerson Hancock it jumped so well in Miller’s normal swing position that the M’s kept him in the normal curve, and instead opted for a piggyback strategy for a while. This didn’t sit well with Miller or Castillo, but the Mariners then went on a six-man trade that will see them through to mid-June, when the club is in the midst of a busy schedule.
It remains to be seen how the M’s will get back to a five-man rotation at that point, especially since Castillo looks his age after a rough start to the season. Castillo has allowed one earned run over his last nine innings, though his ERA still sits at 5.53 over a total of 55 1/3 frames. Castillo’s 4.08 SIERA is very likable and his walk and strikeout rates are about league average, but the veteran right-hander has allowed heavy contact.
Most teams would be more than satisfied with this type of production from a quarterback, however Seattle is in a desirable position to have multiple starters at several positions in the rotation. Despite Hancock’s breakout, George Kirby, Logan Gilbertagain Bryan Woo everything is going well, and Miller has looked great since his return. If this wasn’t enough starting depth, the M’s have several starters (ie Dane Dunning, Randy Dobnak, Jonathan Diaz, Casey Lawrence) with MLB experience down in Triple-A Tacoma, and there has been speculation about that top prospect Late Anderson could go from Double-A to the majors before the end of 2026.
Sinking too far down the depth chart has never been very appealing to the Waters, however, although Hancock’s emergence has been a big help in that regard. The mantra “you can never have enough pitches” rings especially true for a team aiming to make a run at the World Series, so the M’s will be hesitant to move even Castillo unless they are sure they have enough time to start coverage to cover multiple postseason innings.
Castillo’s contract is another reason why the veteran starter for the Mariners is at least open to movement, as opposing teams have asked more about young, controllable arms. Castillo is owed about $14.6MM through the remainder of the 2026 season, $22.75MM in 2027, and the $25MM option for 2028 will be vested if Castillo pitches at least 180 innings in 2027 and finishes the season healthy.
The no-trade protections that existed in Castillo’s extension are now up, so he can be dealt without his consent. That removes one potential obstacle to a deal, though the price tag remains steep for a 33-year-old who could very well be a rotation starter at this stage of his career. Seattle probably has no interest in eating up much of any of Castillo’s salary, and trading Castillo for another player with a hefty contract has only limited appeal, unless the M’s feel that this hypothetical player can help them re-need (perhaps due to the offense).
