Kirby’s Breakthrough Adds Potential Ace To System’s Bevy Of Bats

Image credit: (Photo by Zach Lucy/Four Seam Images)

Long before they worked together, righthander George Kirby was on Sean McGrath’s radar.

“He was in Rye, N.Y., pitching at Rye (High), and I was at Iona in New Rochelle,” McGrath said, “so I had seen him a handful of times throughout his high school career, which is pretty cool.

“Fast forward to the fall of 2017 and I get the opportunity to coach the guy I never thought I’d be able to get at Iona.”

The fall of 2017 is when Kirby landed at Elon, where McGrath had become the pitching coach. At that point, McGrath saw the same intriguing qualities in Kirby that were on display as a high schooler.

“He was athletic and super coordinated,” McGrath said. “He was a strike thrower in high school, and at the time (his fastball) was 88-90, 91-92 (mph). And it was almost like he had an attachment to the strike zone at times, like an unwillingness to leave it.”

Even as Kirby’s stuff ticked up during three years at Elon, his attachment to the strike zone never wavered. He walked six batters in 14 starts as a junior and earned the nod of having the best control among college pitchers in the 2019 draft class. The Mariners drafted him 20th overall.

“Kirby is pretty simple,” a scout said at the time. “He fills the zone and can throw strikes with every pitch.”

That reputation as a control artist only strengthened in his pro debut, when Kirby spun 23 innings in the short-season Northwest League without allowing a walk. His encore performance was delayed a year by the pandemic, which led to the cancellation of the 2020 minor league season and forced all development to be done either at a team’s alternate training site, via remote work or at instructional league.

RELATED: See where Kirby ranks in Baseball America’s Top 100

Kirby was one of the prospects invited to the Mariners’ alternate site in Tacoma, and his progress began to show in big ways during the following spring training. That’s when he unveiled a fastball that had jumped way, way up, all the way to 102 mph.

“It felt great,” Kirby said. “When that happens, your arm just feels so good. Everything comes out nice and easy, you’re not really trying to overthrow, and it just comes out.”

Kirby came out firing at High-A Everett this season. The 23-year-old recorded a 2.56 ERA through eight starts with 50 strikeouts, eight walks and one home run allowed in 38.2 innings.

Beyond his velocity spike, Kirby’s changeup also made impressive strides. Scouts liked it as his best secondary pitch as an amateur, but a change in the way he throws the pitch—based on analytical feedback—has turned it into an even more potent weapon.

The sheer separation in velocity between his fastball and changeup, which is usually around 10 mph, is excellent enough. But now a tweak in the way Kirby grips the pitch has created a version with deeper break.

“Just the idea of having a 10 mile per hour difference is meaningful,” Mariners pitching coordinator Max Weiner said. “When he’s able to do that and then move the ball toward  the outer part of his hand, (while) being driven by the pinkie and ring finger, he’s able to generate meaningful side spin.

“So he’s pushing the ball to the side, which is creating the depth and less horsepower behind the pitch and giving him the velocity separation.”


Kirby’s breaking pitches have come forward, too. His slider has added more sweeping break, and the depth of his curveball gives him another pitch with vertical movement. Combined, Kirby’s arsenal gives him pitches he can use to all quadrants of the strike zone.

“It’s tough, and I think it’s unique because it could change day by day,” Everett manager Louis Boyd said. “There’s times where his curveball just seems unhittable, and then his slider will have an insane amount of sweep to it. And now he’s throwing changeups to righthanded hitters. It’s got to be tough as a hitter to not know what his out pitch is, because he’s got four of them.

“When he locates the fastball at the top of the zone, it doesn’t need to be the offspeed to be an out pitch, so it’s pretty special.”

The most impressive part, however, is that none of the added stuff has come at the expense of his signature command and control.

“To George’s credit, he really evolved, and I think he would say the same thing,” Weiner said. “He’s really evolved his approach from bulk strikes into really quality, strategic strikes, where he’s going to really safe spots in the zone and around the zone.

“That means that instead of moving pitches around for the sake of moving them around, he’s really being intentional about targeting locations where he has extra room to miss, and he’s giving himself margin for error. And I don’t think it takes too long to watch him to realize he doesn’t need all that room. When that skill set and that approach converges on a singular point like that, the results are pretty exciting.”

Kirby ranked as the Mariners’ No. 7 prospect heading into the season, so he certainly wasn’t anonymous or lost in the shuffle. Even so, all the headlines in Seattle’s system went to the dynamic outfield duo of Julio Rodriguez and Jarred Kelenic as well as burgeoning shortstop prospect Noelvi Marte.

So when word began to get around this spring about just how much Kirby’s stuff had jumped—without any sacrifice in control or command—the industry quickly had another name to add to the list of high-end prospects in a system that entered the year ranked only behind the Rays’ cornucopia of talent.

Multiple evaluators from rival teams have pegged Kirby as a top-of-the-rotation starter, thanks to his combination of athleticism, stuff and command.

“His stuff is explosive, and beats hitters at the top of the zone,” one scout said. “I have him at the top of the rotation with a unique power and precision package.”

Two of the final elements that have helped Kirby elevate himself to one of the best pitching prospects in baseball are confidence and drive. He knew a breakout season like this was possible, then worked like heck to make it happen.

“Yeah, I expected it,” he said. “I stuck with my weighted ball program and I did a better job with my body in the offseason, so I think it all came together.”

Kirby wasn’t the biggest name on the Everett pitching staff entering the season. That honor belonged to righthander Emerson Hancock, whom the Mariners drafted sixth overall out of Georgia in 2020.

The 22-year-old Hancock entered professional ball needing to tweak his fastball to have it play better when thrown up in the zone. Before Hancock injured his shoulder in July, the Mariners liked the growth they had seen out of the pitcher whom Baseball America ranked as the top righthander available in the 2020 draft.

The results were there, too. With Everett, Hancock pitched to a 2.42 ERA in 26 innings, spanning seven starts. He struck out 25 and walked 11.

Aside from the results, the biggest goal for Hancock was learning how to deploy his fastballs with two-seam and four-seam life. He uses the same grip on both pitches, but the ball is held differently in his hand to create one pitch that played up in the zone and another with lateral movement.

“When you can get to the end of the spectrum from a northern movement standpoint on a fastball with velocity, and then move toward the east (Hancock’s arm side) with a sinking, running fastball, it’s uncommon,” Weiner said. “You don’t watch many baseball games and see people throwing riding four-seamers and sinking two-seamers, so distinguishing the pitches distinguishes him.”

Between their draft pedigree and early-career performance, Kirby and Hancock were the two biggest names on the Everett pitching staff. But the rest of the staff is not to be discounted.

In particular, 23-year-old Matt Brash has leapt forward into the upper tier of Seattle’s system. The Mariners acquired him from the Padres last July in the Austin Nola deal.

Brash is a Canadian righthander whom the Padres drafted in the fourth round in 2019 out of Niagara. Through 42.1 innings this year he struck out 62 and walked 25.

“The action on his pitches is electric. The stuff that he produces on a daily basis is phenomenal,” Boyd said. “He’s someone who is, for sure, under the radar. And I don’t think it’s going to be under for much longer . . .  His fastball is in the upper 90s, his slider is what we call the demon slider—it’s disgusting.”

But wait, there’s more.

The AquaSox rotation in the first half also boasted lefthander Brandon Williamson, whose huge curveball flummoxed hitters in the High-A West until the Mariners moved him to Double-A. By then, the Texas Christian product, who was taken a round after Kirby in 2019, had whiffed 59 in 39 innings.

The back of the rotation also had 23-year-old righthander Levi Stoudt, who can get swings and misses with a fastball that sits between 95-98 mph and a nasty split-fingered changeup. The Mariners note that Stoudt has four pitches which feature 20-plus inches of break in all four cardinal directions.

There’s also 21-year-old righthander Juan Then, who was already on the Mariners’ 40-man roster and had to be reacquired after Seattle traded him to the Yankees in 2017 for reliever Nick Rumbelow. Then has a whip-quick arm that generates upper-90s fastballs and sweepy sliders, which through nine starts had equated to roughly a strikeout per inning.

And that’s just the arms.


When the AquaSox released their roster, it was clear that 20-year-old outfielder Julio Rodriguez, a supremely gifted hitter and one of the top prospects in baseball, was the team’s crown jewel. He entered the year ranked behind only the Rays’ Wander Franco and the Orioles’ Adley Rutschman among the Top 100 Prospects.

For two months, the only relief teams in the High-A Northwest got from Rodriguez was when he left Everett to help the Dominican Republic qualify for the Olympics. Otherwise, he spent just more than eight weeks tormenting pitchers throughout the Pacific Northwest.

When he was promoted to Double-A Arkansas on June 29, Rodriguez was hitting .325/.410/.581 with six home runs, 21 RBIs and five stolen bases in 28 games. In the second series of the season, against Tri-City, he doubled three times and slammed five home runs.

“I put the highest grade we can put on him aside from what we put on Hall of Famers,” one scout said. “It was like holy s—. It’s easy 6 hit, 7 power (on the 2-8 scouting scale), and I might even go 7 hit and 7 power.  The at-bat quality can be elite. He can be a .290 hitter with 30 home runs.”

In all, Everett’s first-half team was easily the best in the Seattle farm system and could stack up with upper-level clubs like the Royals’ Double-A Northwest Arkansas affiliate, headlined by shortstop Bobby Witt Jr., first baseman Nick Pratto and catcher M.J. Melendez; and the Rays’ Triple-A Durham club, which at various points hosted some of Tampa Bay’s top talent, including shortstop Wander Franco, second baseman Vidal Brujan, righthander Luis Patiño and outfielder Josh Lowe.

“(The Everett group was) pretty special. They are recognized by multiple outlets as being one of the most talented minor league teams in baseball, and I don’t think they’ve disappointed,” Boyd said.

“They’ve shown up day in and day out and put in the work that they’ve needed to get better—even though they already have a lot of talent—to turn that into usable skill. And I think that’s played out a lot during our season so far.”

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