Which Pitcher Would Start Game 1 of a Playoff Series For Seattle Mariners?

At 63-53, the Seattle Mariners enter play on Friday in possession of the second wild card in the American League playoff picture. They are just 1.5 games back of the Houston Astros in the American League West as well.

And look, Seattle has to handle its business over the final 46 games of the season in order to actually clinch a playoff berth, but let's have a little fun looking ahead.

Which M's pitcher would start Game 1 of a playoff series, if the team had its full complement of choices?

My choice

At this point, my choice would be Bryan Woo. An All-Star this season, Woo has been the best and most consistent starter for Seattle. At 9-6 with a 3.02 ERA, he's generally found a way to limit damage. Having gone six innings or more in all 22 of his starts, he's been efficient with his pitch count and will be able to save a bullpen for the rest of a series in all likelihood.

Bryan Woo has gone 6+ innings in ALL 22 of his starts this season 😳#MLBCentral | #TridentsUp | @Mariners pic.twitter.com/vbjbfpuI8A
— MLB Network (@MLBNetwork) August 6, 2025

I asked ESPN MLB Insider Buster Olney about this question, and told him my stance. Here was his answer:

But I think that, if the relationship with the manager and the players is about, 'okay, what's our best chance to win today', then the other pitchers will be okay with that. If it's about stature, and it's about Luis Castillo's track record and 'he's the leader of the staff' and about comfort level, like, I don't know, Brian Woo. I'm not around the Mariners every single day, so I can't tell you how he feels about it. But there are certainly guys who feel better about pitching a game two or three than a game one. That would all factor in. But I think in terms of performance, what you're saying is absolutely reasonable.

Luis Castillo

To Olney's point, Castillo is the elder statesman on the staff, and he has the respect of his manager of rotation mates. Does Wilson defer to the longtime leader of the staff? Furthermore, Castillo started Game 1 of the 2022 wild card series, which the Mariners won. He also started Game 2 of the ALDS against the Astros, pitching very well also.

Luis Castillo, Vicious 88mph Slider. 😤 pic.twitter.com/ApbMObaeKC
— Rob Friedman (@PitchingNinja) May 25, 2025

George Kirby

Kirby has been more uneven this season, entering the weekend at 7-5 with a 4.04 ERA. He's had the best strikeout-to-walk ratio in baseball in each of the last two seasons, so his ability to throw strikes is certainly necessary in the playoffs. Furthermore, he dominated the Astros in Game 3 of the 2022 ALDS, throwing seven shutout innings, so playoff experience is on his side.

George Kirby playoff highlights to cleanse the mind of Mariners fans. pic.twitter.com/8RZmwiZ07m
— Steve (@MarinersSteve) December 14, 2023

Logan Gilbert

Also uneven this season because of injury, Gilbert is just 3-4 with a 3.35 ERA. However, he has the best strikeout stuff on the M's staff. The best way to limit damage is to not allow the other team to put the ball in play, and Gilbert does that better than anyone on the staff. He's fanned 118 batters in just 83.1 innings.

However, with just three quality starts, he can't be counted on going deep into games, at least not yet.

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My choice

Luis Castillo

George Kirby

Logan Gilbert

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