Mariners have huge decision in Game 5 starting pitcher

October 9th, 2025

DETROIT -- Following the Mariners’ 9-3 loss to the Tigers in Game 4 of the AL Division Series on Wednesday, manager Dan Wilson was not ready to announce who would take the ball for Seattle in Friday’s decisive Game 5 at T-Mobile Park.

It all but assuredly will be one of or , the two right-handers who opened this series for the Mariners and started Games 1 and 2 in Seattle last Saturday and Sunday. Both would be on normal rest on Friday.

But whether it’s Kirby or Castillo, one thing is certain: The Mariners’ starting pitcher will be their biggest X-factor as the club looks to punch its first ticket to the AL Championship Series since 2001.

The Mariners’ starting rotation has dominated at home all season. They will need it to step up again, as Seattle looks to knock off Detroit ace Tarik Skubal once more, this time for all the marbles.

“It will be a lot of fun to watch,” said Bryce Miller, who allowed two runs on four hits and two strikeouts over 4 1/3 innings on Wednesday.

“We’ve got a lot of good options. We've thrown the ball really well and thrown the ball well this series, for the most part. I’ve got confidence in whoever's going, they’ll do that.”

They’ve thrown the ball well all season, certainly in Seattle. Mariners starters ranked fourth in MLB in ERA at home (3.30) and led in innings pitched (450 2/3). Kirby recorded a 3.38 ERA in 66 2/3 innings over 12 starts. Castillo had a 2.60 ERA in 100 1/3 innings over 17 starts.

There could be a scenario where both Kirby and Castillo pitch, given that Seattle will have all hands on deck with its season on the line. In any event, the starter needs to set the tone and go toe-to-toe with Skubal, the presumptive American League Cy Young Award favorite.

That certainly is true given how the Mariners’ offense has fared against the lefty this season.

Seattle is the only team that Skubal lost to twice in the regular season. Over a combined 10 2/3 innings, the Mariners tagged him for seven runs on 10 hits (including two homers) and five walks.

The Mariners also beat Skubal for a third time this year on Sunday, in their 3-2 win in Game 2 of this series. Skubal allowed two runs on five hits (including a pair of Jorge Polanco solo homers) over seven innings.

“We've been able to get to Skubal throughout, and we have another chance to do that on Friday,” Wilson said. “Offensively, we've done some really good things in this series and continued to do some of those things today. So we will certainly be ready on Friday.”

Getting a quality performance from Friday’s starter is key for a few reasons. Looking at the bullpen, four Mariners relievers covered 3 2/3 innings on Wednesday: Gabe Speier, Eduard Bazardo, Carlos Vargas and Luke Jackson.

Bazardo has pitched every game this series, Speier and Matt Brash have pitched in three. There could be some concern over a lineup seeing the same pitchers that frequently often over a short stretch.

Even with an all-hands on-deck scenario, Seattle’s starter providing length and pitching well could make the blueprint to victory clearer.

It’s all on the line for the Mariners on Friday, and their confidence was steadfast even after the Game 4 loss.

“Everything's in front of us,” Wilson said. “These guys have done this all season long, where they get in tough situations and they know exactly what to do. And they do fight back, and they do bounce back. I'm not worried about that at all. No better place to do that than at home.

“I think we just continue to do the things we've been doing and just get back on the right track on Friday.”