Mariners name George Kirby Game 1 starter of ALDS vs. Tigers

Adam Jude, The Seattle Times on Oct 3, 2025

Published in Baseball

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SEATTLE — George Kirby threw a gem in the Mariners’ last home playoff game in 2022.

He’s getting the chance to do it again in the Mariners’ next playoff game.

Kirby, the 27-year-old right-hander, has been named the Mariners’ starter for Saturday's Game 1 of the American League Division Series against the Detroit Tigers at T-Mobile Park, manager Dan Wilson announced Friday.

Luis Castillo will start Game 2 for the Mariners on Sunday.

Super honored," Kirby said. "It's a big game and something you always dream of, to start Game 1 or any game in the playoffs."

In his first career playoff start, Kirby threw seven shutout innings against the Astros on Oct. 16. 2022, the only playoff game the Mariners have hosted since 2001. The Astros went on to win 1-0 an epic, 18-inning thriller.

A few days earlier, in his only other postseason outing, Kirby made his first and only professional relief appearance to close out the Mariners' Game 2 wild-card series victory over the Blue Jays in Toronto.

Mariners manager Dan Wilson said the drastic home/road splits for Kirby and Castillo were factors in the decision to choose them to pitch this weekend over Logan Gilbert, the Mariners' No. 1 starter in 2024 and the opening-day choice this season.

Kirby made 12 starts at home this season, posting a 3.38 ERA over 66 2/3 innings, with a .227 batting average against and a .627 OPS.

On the road, Kirby had a 5.16 ERA in 11 starts, with a .279 batting average against and a .761 OPS over 59 1/3 innings.

Similarly, Castillo posted a 2.60 ERA in 17 starts at home during the regular season compared with a 4.71 ERA in 15 starts on the road.

Kirby made one start vs. the Tigers this season, allowing four runs in five innings in a 15-7 victory in Detroit on July 12.

Castillo is 2-0 with a 3.75 ERA in two starts vs. the Tigers this season.

Castillo also has a strong track record in the postseason, posting a 1.83 ERA with a 19-to-1 strikeout-to-walk ratio in 19 1/3 innings. In his first postseason start for the Mariners in 2022, Castillo tossed 7 1/3 scoreless innings in Game 1 in Toronto.

“Starting pitching is one of our strengths, and we trust anybody that goes out there to give us a solid outing,” Wilson said. “Right now, the way things stack up, it will be George in Game 1 and The Rock in 2.”

Gilbert will almost certainly start Game 3 in Detroit on Tuesday, though Wilson stopped short of making that a formal announcement.

Another major factor is the uncertainty surrounding Bryan Woo, the Mariners' 25-year-old All-Star who is nursing an injury in his pectoral muscle.

Woo threw 15 pitches off the T-Mobile Park mound Thursday and then indicated he probably wouldn't be available for another week.

It's possible Woo could be left off the ALDS roster, though that decision won't be formalized until Saturday morning.

Kirby opened the season on the injured list because of shoulder inflammation, the first major injury of his career. He made his season debut May 22 in Houston, where he allowed five earned runs in just 3 2/3 innings. He was touched up for six runs over five innings in his next start, a 9-0 loss at home to the Nationals.

"It takes a little bit, you know, just to kind of trust your body again and have that same sort of confidence," he said.

Kirby was fairly steady through the summer months, until a blowup start against the Rays on the road Sept. 3 when he surrendered eight runs (seven earned) in two innings, the shortest start of his career.

He closed out September with four strong starts, and his performance in Houston on Sept. 20 — six shutout innings, seven strikeouts, no walks — was one of the Mariners' most important starts of the year.

His late-season resurgence, he said, is owed in part to his relationship with Adam Bernero, the team's mental-performance coach. Bernero asked Kirby to start writing down his thoughts and feelings in a journal.

"It's been super helpful … [to] just get your feelings out, don't leave anything on the table," Kirby said. "It allows me to forget about a lot of things, whether it's a bad game or just some, like, stress or anxiety leading up to something. It allows me a little freedom to just worry about the game instead of everything else that goes along with it."

The Tigers are expected to start 25-year-old right-hander Keider Montero in Game 1, which could turn into a “bullpen game, meaning they’ll use a handful of relief pitchers to mix and match throughout the game.

Reigning AL Cy Young winner Tarik Skubal, the former Seattle U standout, is expected to start Game 2 for Detroit on Sunday night. The Tigers will announce their pitching plans Friday afternoon.