George Kirby, Like John Paul Jones, Is a Mariner With Elite Command

What’s the most important thing for a pitcher to do? That’s right, don’t leave the ball up in the zone for Aaron Judge. The second-most important thing for a pitcher to do is throw strikes. Throw strikes to get ahead in the count, throw strikes to challenge hitters, throw strikes to force action early in the count and keep your pitch count down… pitchers talk about throwing strikes the way health nuts talk about kale. It’s good for you. How? Let me count the ways.

Except, nobody actually throws strikes. Last season, 347 pitchers threw at least 50 innings in the majors; nobody threw more than 58.5% of their pitches in the strike zone. Devin Williams, one of the best in the business, worked inside the zone just 42.4% of the time. “It’s good to throw strikes,” then, is something to be taken seriously but not literally.

Seattle Mariners right-hander George Kirby is a greater adherent of the zone than most. Last season, he broke a big league record by throwing 24 consecutive strikes to start a game. This year, he’s working in the zone more than any other pitcher with at least 20 innings under their belt. It was not always thus.

Kirby says he was not born with some preternatural ability to throw strikes. Like Saint Paul on the road to Damascus, there was a moment of spiritual conversion that turned him into the strike-thrower he is now. Kirby’s came as a college sophomore.

“Up until that point I was like any other guy, just walking people, whatever,” he says. Now, “trying to beat guys in the zone is my whole mentality. I hate giving free bags, so I’m going to do my best to be in the zone.”

Wait, just like that? He just woke up one morning and decided he was through walking people?

“Pretty much.”

The way Kirby tells the story makes it sound like he was some profligate chucker before his conversion, which isn’t the case. In his first two seasons at Elon University, Kirby walked 2.6 batters per nine innings. But that summer in the Cape Cod League, Kirby struck out 24 batters in 13 innings and walked just one. That’s the kind of performance and venue that builds first-round buzz for a mid-major pitcher, particularly one whose draft year goes like Kirby’s: 14 starts, 88 1/3 innings, a 2.75 ERA, with 107 strikeouts and just six walks. And sure enough, the Mariners took him 20th overall in 2019.

Kirby continued to pound the zone as a rookie. Last year, out of 140 pitchers with 100 or more innings pitched, he was fifth in zone rate and sixth in walk rate. This much you probably knew already; “throws lots of strikes” is the one-sentence scouting report on Kirby.

But it’s a dangerous life Kirby’s chosen to lead. Most pitchers try to fool the hitter into swinging at a pitch he was never in danger of putting in play. Working in the zone as much as Kirby does, even a minute mistake in location can result in extra bases. It’s not a huge margin for error, but he has a process.

“Going inside to hitters to make them uncomfortable,” he says. “When I do that, it makes my off-speed pitches better. And when I’m able to throw my off-speed for strikes early, that lets me expand the zone more, and I need to for that swing-and-miss.”

Kirby throws five pitches — a four-seamer, sinker, slider, curveball, and changeup — and says that repertoire is the result of careful editing. He could throw more, he says, so why did he choose these five?

“Whatever pitch I can throw full-effort is what I’m thinking,” he says. “Something to keep them all deceptive, something that looks like a heater, something I can command. I could throw some other pitches too, but they’re not in the command space I need.”

The most recent addition to Kirby’s repertoire is a slider he added, or at least refined, last year. Baseball Savant registered his old slider as a cutter, adding to my ever-present and ever-increasing rage at the baseball community’s inability to decide what the hell a slider is.

“I guess it’s just whatever they think in their head that they’re throwing,” Kirby says of the ongoing issue in pitch nomenclature. “If you’re throwing a bullet slider, it’s a cutter, but I don’t know, there’s no science to it.”

Kirby’s new slider is a few miles an hour slower than the old one, which came in around 88, but it also features elite break, particularly horizontally. He says the older slider blended with his fastball too much, so he wanted something with more movement. In a small sample this year (57 pitches and 15 batted ball events), the new slider is getting knocked around a bit, but Kirby thinks that it’s developing well.

“If I can get it back up to 87 or 88, I think that’d be perfect,” he says. “Kind of like Matt Brash, though it’ll be hard to be that nasty…Right now, I’m using a spike grip, so it’s hard to get the velo I want out of it. But the more I throw it, the more comfortable I feel. I’m tinkering with some wrist supination.”

If Kirby pulls that off, he’ll have a true out pitch to go with his excellent command. Hitters don’t know what’s coming, but they know it’s going to be somewhere in or near the strike zone, which means they swing a lot. Last season, among pitchers with 100 or more innings, Kirby was ninth in Z-Swing%. (Three other Mariners starters — Chris Flexen, Robbie Ray, and Logan Gilbert — were in the top 15.)

Apart from his changeup, which is mostly utilized against left-handed batters, Kirby doesn’t view any of his pitches as having a specific purpose: one for swing-and-miss, another for groundballs, and so on. His best whiff generator is his four-seamer — 31.9% this year, in a small sample — while his sinker and breaking balls all generate swings and misses in the teens.

“I’ve just got to throw every pitch with full intent,” Kirby says, “whether it’s with two strikes, where it’s more like a [expletive] you attitude, or early in the count, making sure they’re in the zone. [When hitters] respect that, I’m able to get outs.”

Anyone who throws tons of strikes invariably reminds people of Greg Maddux, with the assumption that a pitcher with great command is also a master of the chess game between pitcher and batter. Kirby gets involved in game planning, but once the national anthem is over, he prefers to let his catchers, Cal Raleigh and Tom Murphy, call the game however they like.

“I’m just trusting Cal and Murph,” he says. “I like to keep the thinking to a minimum.”

Whatever they call, Kirby will hit his spot. Last season, he was third in Location+ among pitchers with 100 or more innings. On the Baseball Savant leaderboard, 275 pitchers recorded at least 250 batters faced; of those, Kirby ranked 21st in Edge%, or the proportion of his pitches that hit the frontiers of the strike zone.

And that’s the key — pitching at the edge of the strike zone without leaving too many hittable pitchers over the heart of the plate. Kirby is one of few pitchers who can get hitters out without surrendering free bags. He hates doing that, you see.