You’d be forgiven for focusing your attention on baseball’s No. 3 overall prospect, Mariners outfielder Julio Rodríguez, heading into the season. But the latest of Seattle’s promising young arms debuted last week.

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And while his was met with a slightly less fanfare from a national audience, make no mistake: George Kirby is one of the most important pieces of Seattle’s road back to the playoffs.

The 24-year-old righty was the Mariners’ top pitching prospect when he was called up for a Mother’s Day start against the Tampa Bay Rays.

“The biggest thing for me (was) just to focus on my breath and just try to do things one step at a time,” Kirby said of his debut during a Monday interview with Jake and Stacy. “Not think too much. Just breathing and getting that under control has been super helpful on the mound. Definitely calmed me down a bit with all the adrenaline going through my body. That was the biggest thing for sure; just trusting who I am and doing what I did to get up here. I’m not trying to change who I am as a pitcher.”

To his credit, what he did to get here is pretty exceptional. In 2021, Kirby compiled 15 starts between High-A Everett and Double-A Arkansas, compiling a 2.53 ERA (and 80 strikeouts) over 67 2/3 innings pitched.

During his interview on Jake and Stacy, Kirby talked about what he worked on heading into the season, the kind of pitcher he wants to be, and what goes into the pitches he decides to use on the mound.

The offseason change: grip on the slider

“I was really focused on sweep with my slider,” Kirby said of his altered grip. “And for me it just didn’t really feel natural. I wasn’t able to command it as well. So, the last month or so I’ve really just honed in on throwing it more like a fastball. Just applying more pressure to that middle finger, allowing me to throw it like a fastball has allowed me to throw it harder, like 88-91. And it still has a similar movement profile but the biggest thing for me is just command with that pitch. I’d like to use all my weapons in any count and come back in counts and try to get a strikeout. So that’s been the biggest thing; just trying to command the pitch really well.”

The regular season plan: Make it a toss up for hitters

Kirby has already diversified his pitching repertoire from last year to include his secondary pitches more often.

“Over the past few years I was pretty heavy with my fastball,” Kirby sad. “Usage was probably 50 to 60 percent. This whole season during spring training I really tried to hone in on making my usage a toss up to hitters. I just really want to be able to throw any pitch in any count… recently I’ve been more like 35 to 40 percent with the fastball, 27 with the slider, 23 or 25 with the change up, and 17 with the curveball. Right there, that’s a great usage for me, and I want to continue that. These last two starts I did throw a little bit more fastballs than I’m used to. It was something I talked to (Luis) Torrens about. They weren’t putting great swings on it so you might as well just keep pounding that pitch.”

How do you manage what pitches you’re using?

“Sometimes your gameplan has to change. You read the hitter’s swings, stuff like that. You come back to the dugout, talk with the pitching coach, go over the next three guys, see what you need to change up. But especially my curveball; if I’m getting really good bite on it, that’s something I’ll start using more in later counts to try to get a swing and miss. Same with the change up or slider. If I’m getting more bite on it, I’m starting in the zone better, and I can backfoot it, that’s also a great option. Or if I see a guy not going for that, I can go up and in on him. So a lot of stuff changes with that.”

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