The Mariners are back where they’ve been so often this summer: juggling starters, adjusting rest, and explaining why the rotation never quite looks settled.
Only this time, the wrinkle arrives with Kade Anderson making his major league debut. Twenty days after the club traded Luis Castillo to the Chicago White Sox on Aug. 2 and finally went back to a standard five-man setup, Seattle now has six starters back in the mix.
That’s the real story here. Not that the Mariners somehow had “too many” starters, but that they had six arms and didn’t always want to use those exact six. The numbers never really told the full story.
Anderson forced the issue in the best way possible. The 22-year-old left-hander was electric at Double-A Arkansas, going 10-1 with a 1.06 ERA in 18 starts.
He piled up 135 strikeouts, issued just 13 walks and allowed 47 hits over 93 1/3 innings. A performance like that doesn’t stay buried for long.
Bryan Woo’s shoulder soreness opened the door right now, though the Mariners had already been moving pieces around before that. Woo had been lined up to start Saturday before exiting his previous outing after 75 pitches, so giving him extra recovery time made sense. It also fits the broader pattern Seattle has been living with for months: rest when needed, shuffle when necessary, and explain it all after the fact.
Back in late July, Dan Wilson moved Woo up a day and pushed Bryce Miller back. Miller had already worked through an oblique injury and had benefited from extra time at other points.
This wasn’t a staff locked into a clean five-day rhythm. The Mariners were building in breathing room whenever they felt a starter needed it.
That’s what made the messaging around the rotation so messy. When Miller first returned in May, Wilson said the team would use six starters temporarily and then “recalibrate.” Seattle wanted Woo, Logan Gilbert and George Kirby on the mound as often as possible, so it moved toward a Castillo-Miller piggyback arrangement.
The results were good. The optics were not always great.
Castillo slammed his glove after being lifted from one outing, and Miller said he didn’t know until two days beforehand that he would be the pitcher coming out of the bullpen. The Mariners later admitted the communication breakdown and shifted back to a straight six-man rotation.
Then the schedule changed, and so did the explanation.
General manager Justin Hollander said a six-man rotation paired with off-days could put starters on seven-day programs. That led to a rotating piggyback setup involving all six pitchers.
Hollander also took responsibility for the earlier confusion, saying the communication failure was “100 percent on me.” Even that arrangement didn’t last long.
None of this changes the fact that trading Castillo made sense. Seattle found a team in the Chicago White Sox willing to take on approximately $30 million in guaranteed money through the end of 2027. In return, the Mariners picked up veteran reliever Seranthony Domínguez and catching prospect Boston Smith, while moving on from an expensive starter.
Castillo also deserved a cleaner explanation than the one the rotation shuffle provided. He mattered to this stretch of Mariners baseball, was a respected clubhouse presence, and was the pitcher who helped signal that the rebuild was over in 2022. By 2026, he was 33, overpaid, and standing in Kade Anderson’s way.
So yes, six starters are back. But the real answer has been there all along: the Mariners were never short on pitchers. They just didn’t want to keep using that particular group of six.
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