Rookie George Kirby’s recent run for Mariners should have your attention

Aug 27, 2022, 1:49 PM | Updated: 4:04 pm
Mariners George Kirby...
George Kirby throws a pitch against the Washington Nationals at T-Mobile Park on August 24, 2022. (Alika Jenner/Getty Images)
(Alika Jenner/Getty Images)

For the second season in a row, a highly-touted right-handed rookie has become a key part of the Mariners’ starting rotation. And what’s interesting about that is George Kirby this year is pitching even better than Logan Gilbert did a year ago.

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Gilbert, Seattle’s first-round pick in 2018, debuted last May and made 24 starts, going 6-5 with a 4.68 ERA, 3.73 FIP and 128 strikeouts to 28 walks. His presence in the Mariners’ rotation was critical as multiple starting pitching options got hurt early in the year or really struggled out of the gate.

This year, it’s Kirby, Seattle’s first-round pick in 2019, who has turned heads. And he’s been even better than Gilbert was in 2021.

Kirby just wrapped up his 18th MLB start and it was a dandy. He went seven innings and allowed just one run against the Washington Nationals on Wednesday while striking out nine batters, tying a career high. Kirby started the game with 24 consecutive strikes, which is a new MLB record since pitch tracking began in 1988, well before the Elon alum was born.

Through his first 18 starts, Kirby is putting together quite the rookie campaign. In 97 2/3 innings, the young right-hander has been worth 1.2 WAR while going 5-2 with a 3.32 ERA, 3.18 FIP and 1.198 WHIP. He’s struck out 102 batters while walking just 18, and he’s allowed 9.6 hits per nine innings, 1.1 homers per nine, 1.2 walks per nine and has struck out 7.85 hitters for every walk allowed.

And Kirby, who is as elite a strike-thrower as there is in MLB, has the advanced/expected numbers to show that what he’s doing is no fluke. His season ERA of 3.32 is just 0.02 points off his expected ERA of 3.30, per Statcast. Additionally, opponents are hitting .268 off the rookie while Statcast pegs his expected batting average against at .233.

And Kirby just gotten better as the season has progressed.

Kirby hit a low point on June 27, allowing seven runs to the Baltimore Orioles, and opposing hitters swatted four home runs off him that day. That gave Kirby a 4.08 ERA through his first 10 career starts, and he’d allowed 12 homers in 53 innings pitched.

But since that rough outing, Kirby has been on another level.

In his last eight starts, Kirby has thrown 44 2/3 innings with a 2.42 ERA and 1.35 FIP while opponents have a combined .604 OPS off him as he’s pounded the zone for a 69% strike rate. He’s struck out 53 batters and walked only six, and of the 46 hits he’s allowed, just seven have gone for extra bases. Additionally, Kirby has allowed three runs just once over those eight starts.

And those four homers he allowed against Baltimore? Those were the last home runs Kirby has allowed period.

What makes this run even more impressive is that Kirby’s workload is being watched very closely by the Mariners.

The rookie hurler has a very limited track record of throwing considerable innings dating back to his time in college. Kirby’s career high in innings at Elon was 90 1/3. In his first pro season in 2019, he threw just 23 innings shortly after being drafted. 2020 was a lost year of sorts as Kirby spent the year at the Mariners’ alternate training site as there was no minor league season, and last year he threw just 67 2/3 innings between High-A and Double-A.

As such, the Mariners have been very open about keeping an eye on the young right-hander’s workload, and he’s typically been on pitch counts in his most recent starts.

Over this recent eight-start stretch, six of those outings have come after the All-Star Break. During those first two starts out of the break, Kirby threw just 51 and 74 pitches, respectively. Over his last eight starts, Kirby has thrown 85 or more pitches four times, with only two of those coming after the All-Star Break. Pitch counts haven’t stopped Kirby from working deep into games, though, as he’s gotten into the sixth inning in each of his last four appearances.

So how has Kirby had the success he’s had this year, especially his last eight starts?

First and foremost, a big reason Kirby has been as good as he’s been of late is he’s limiting hard contact and keeping the ball in the ballpark. It sounds simple, but when you consider how Kirby is always in and around the zone, that can allow opposing hitters to be very aggressive early in counts in order to try and do considerable damage. That happened to him at times earlier in the year, but in addition to throwing a lot of strikes, the quality of those strikes thrown appears to have improved as well.

Additionally, Kirby’s 4-seam fastball and a new weapon have been especially good for him.

The arsenal

Kirby leans on the 4-seam fastball, using the pitch 46.9% of the time, per Statcast. And that’s for good reason. Statistically, that’s been his best pitch, and he’s leaning on it accordingly.

Opponents are hitting just .219 off the heater and slugging .344 off it. Aside from a new pitch that Kirby has only just recently started throwing in games, the 4-seam fastball has yielded the lowest batting average and slugging percentage against of Kirby’s entire arsenal.

The slider, Kirby’s second-most-used pitch at 21.1%, has gotten hit hard and often this year. Opponents have hit .338 off it with a .558 slugging percentage for four home runs and eight extra-base hits.

Kirby also uses a curveball (14.9%), which is being hit at a .292 clip with a .479 opponent slugging percentage.

There’s also been the changeup, which Kirby uses almost exclusively to lefties. He throws the pitch just 8.9% of the time and opponents have hit .289 off it with a .421 slugging percentage.

But it’s Kirby’s newest pitch that’s really been great for him lately. That would be the 2-seam fastball/sinker, which has also been a great pitch for Robbie Ray and his in-season turnaround.

Opponents have hit .310 off the sinker, but the expected batting average is .218. Opponents have also slugged .310 off it as all 13 hits off the sinker have been singles. It also has the highest “putaway” percentage of all five of Kirby’s pitches at 32.5%.

Additionally, despite throwing the pitch just 8.2% of the time this year (the percentage of which is much higher over this recent eight-start stretch), Kirby has 13 strikeouts on the offering, which trails just his 4-seam fastball and slider in terms of total strikeouts recorded by any single pitch. The offering has been especially effective to left-handed hitters, with Kirby starting the pitch inside off the plate and running it back over the inside corner for strikes, many of them Strike 3.

The 4-seamer and sinker may not be enough to fully lean on for Kirby going forward, but they’ve both shown they can be great pitches for the man who just relentlessly attacks the strike zone. This recent eight-start stretch has shown that.

And with Gilbert and Marco Gonzales looking to find their footing of late, this run the rookie has been on should certainly have your attention. Heck, if the Mariners do end their playoff drought, Kirby may enter the postseason as Seattle’s third-best pitcher and earn himself a playoff start in the Wild Card round.

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Rookie George Kirby’s recent run for Mariners should have your attention