Mariners’ rotation going back to piggyback – with a twist

The Seattle Mariners are returning their starting pitching rotation to a piggyback strategy, but this time it will be a little different.

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The Mariners, who currently have six healthy starting pitchers, will stick to a five-man rotation going forward, with each of the six starters taking turns as the piggyback pitcher who will skip a turn in the rotation to instead throw multiple innings in relief of a teammate.

Mariners general manager Justin Hollander shared the news with reporters prior to the AL West-leading team’s homestand opener Tuesday at T-Mobile Park.

We will get into this more in the pregame show but the Mariners will go with a sort of rotating piggyback the next 30 days going with four regular starts and then the piggyback day with all starters rotating through.

— Shannon Drayer (@shannondrayer) June 16, 2026

The Mariners initially used the piggyback tactic following the return in May of Bryce Miller, who started the season on the injured list, with Miller and Luis Castillo taking turns as the starter and the piggyback pitcher in four games over a stretch of 2 1/2 weeks.

The strategy was not without controversy, with both Castillo and Miller either showing their frustration or voicing a lack of comfort with the plan, but it was more importantly successful on the field. Miller and Castillo combined for a 1.67 ERA during the piggyback run, which also allowed the Mariners to almost completely stay away from their bullpen pitchers on those days.

The Mariners switched to a six-man rotation during their recent three-city road trip where they played 10 games in 10 straight days. Seattle went 4-6 on the trip.

Currently, the M’s have Logan Gilbert scheduled to start Tuesday and George Kirby on Wednesday against the Baltimore Orioles. Wilson said Bryan Woo is set to start the series finale Thursday, with Miller starting and Castillo taking the first turn as the piggyback in Friday’s series opener against the Boston Red Sox. That would leave Emerson Hancock to start Saturday against Boston.

The Mariners (37-36 record) enter Tuesday in first place in the AL West by a half-game over the Athletics. Game 1 against the Orioles will start at 6:40 p.m., with Mariners Radio Network coverage on Seattle Sports beginning at 5:30 with the pregame show.

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