MLB Insider believes pitcher George Kirby could be key to Mariners' World Series hopes

Even with a robust rotation led by 15-game winner Bryan Woo, MLB analyst and Mariners reporter Jon Morosi believes Kirby could be Seattle's most significant starter in 2026

Oct 20, 2025; Toronto, Ontario, CAN; Seattle Mariners catcher Cal Raleigh (29) talks with pitcher George Kirby (68) in the first inning against the Toronto Blue Jays during game seven of the ALCS round for the 2025 MLB playoffs at Rogers Centre. Mandatory Credit: John E. Sokolowski-Imagn Images | John E. Sokolowski-Imagn Images

It's no secret that the Seattle Mariners have one of the very best young rotations in Major League Baseball, with five hurlers all on the front side of their careers. On any given day, any one of them could toss a scoreless outing and secure a win. However, even with a robust rotation led by 15-game winner Bryan Woo, MLB analyst and Mariners reporter Jon Morosi believes righthander George Kirby could be Seattle's most significant starter in 2026.

“When he’s really going, when he’s really at his peak – and we didn’t necessarily see it from start to finish last year – I still think Kirby has the biggest upside,” Morosi said. “I think Woo was obviously their best a year ago. I just think that Kirby, the way that he goes about his craft and the demeanor, the stuff. I think that when I look at the body and the delivery, there’s a lot of projection and ability to say he is going to stay healthy and be a durable ace for a long time.”

MLB Network's Jon Morosi believes a better 2026 from George Kirby could be key to the #Mariners getting over the top and reaching their first World Series.

"I still think Kirby has the biggest upside," Morosi said of Seattle's talented starting rotation.https://t.co/rCCO2ODWAM

— Seattle Sports (@SeattleSports) February 28, 2026

Kirby, who just turned 28 this month, was the club's first-round selection in the 2019 draft and debuted at the big league level in 2022. A one-time AL All-Star, he's shown great stuff, but has yet to fully achieve numbers that match his titanic talent. At the same time, he's compiled a winning record, 45–34. But Morosi's point, that Kirby could be the most valuable number two or starter in the game, is valid. It would be the type of strategic luxury that most World Series winners display.

Will 2026 be a banner year for Kirby and the M's?

Oct 15, 2025; Seattle, Washington, USA; Seattle Mariners pitcher George Kirby (68) walks to the dugout before the game against the Toronto Blue Jays during game three of the ALCS round for the 2025 MLB playoffs at T-Mobile Park. Mandatory Credit: Steven Bisig-Imagn Images | Steven Bisig-Imagn Images

Considering his past success and the fact that some of his progress has been slowed due to some injuries over the last few years, there's definitely reason to believe that this could very well be Kirby's breakout year. If he steps up, and Woo just keeps developing as an elite ace? Then, a lot of the pieces of the puzzle will already be in place for Seattle to make a Series run.

“I think he is the person for whom he could boost the 2025 performance the most … heading into ’26 in such a way that really does take the Mariners from being a really good team and maybe even a great team to a World Series team,” Morosi said. “… If Gilbert and Woo maintain ‘25 and then we get the best of Kirby, to me, there is not a team in the American League that is better than the Seattle Mariners.” [Hear the full conversation by clicking HERE ]