George Kirby, other Mariners starters working on new pitches this spring

PEORIA, Ariz. – If you didn’t add a variation of a split-finger fastball to your pitch repertoire this offseason, you were doing it wrong as a pitcher for the Mariners.

For their own various reasons, apparently all the cool kids are doing it this spring.

OK, that might be a bit of an exaggeration. But it appears that three-fifths of the Mariners’ starting rotation started experimenting with the pitch this offseason with the intent of adding it to their pitch mix for 2023 season. Right-hander George Kirby confirmed that he, too, is working on a split-finger pitch this spring. He joins fellow rotation mates Robbie Ray and Logan Gilbert, who have also been working to add the pitch.

With Marco Gonzales trying to implement a slider to his arsenal, it leaves only Luis Castillo as a pitcher not trying to add a new pitch.

Then again, when you are as dominant as Castillo and everything you throw is considered nasty, adding a pitch isn’t really necessary for success.

There wasn’t some group text among the starters about adding a split-finger. It was organic for each of them.

It would’ve been more fun if Kirby decided to throw the split-finger to one-up Ray in the same way he did with the two-seam fastball at midseason in 2022.

But that wasn’t the case.

“We kind of all came in and Logan said, ‘Yeah, I’m throwing a splitter,’ and I was like, ‘I’m throwing a splitter, too,’” Kirby recalled. “I think it’d be a really good pitch if we all get that going. And it’s good now that we’re all throwing it because we can kind of take some things here and there from each other.”

Kirby’s arsenal includes a four-seam fastball that hits 97 mph and the newly added two-seam fastball that sinks away from left-handed hitters at 95 mph. He also has a curveball, a slider and a change-up.

So why another pitch?

“I just want something that I could throw more like a heater with more deception, something with a little more depth and possibly get a little more swings and misses and some weaker contact,” he said.

When it’s thrown properly, what should it do?

“I throw it like a heater and just falls off the table with more vertical movement,” he said. “And I still have my change-up, which is more horizontal in movement.”

Kirby threw two change-ups in his first Cactus League start on Saturday. They were both 87 mph and, ideally, he’d like to see an 8 to 10 mph difference from his fastballs.

“It was 50-50 today,” he said. “I threw one good one that I got Cole Tucker to roll over on and I threw another that went to the backstop. So I’ve got some work to do.”

Servais likes that Kirby is working to improve. But he also doesn’t want him to forget who he is and what makes special – the ability to overwhelm hitters with strikes from his established pitches.

“I’m not as curious with him as maybe some other guys,” Servais said about seeing the splitter results.

Kirby’s rookie season was a success by all standards other than his own. He made 25 regular-season starts, posting an 8-5 record with a 3.39 earned-run average. In 130 innings, he struck out 133 with just 22 walks.

He made two appearances in the postseason. He got the save in the clinching game of the American League wild-card series, pitching a scoreless inning to secure Seattle’s comeback, 10-9 win.

He started Game 3 of the American League Division Series, pitching seven shutout innings and allowing six hits with no walks and five strikeouts.

Coming into last season, Kirby had never thrown more than 70 innings in a professional season. With his 24⅔ innings to start the season at Double-A Arkansas, two in a midseason start with Triple-A Tacoma and the eight in the postseason, he threw 164⅔ innings in 2023. It was almost 100 more innings than the 67⅔ innings he pitched in 2022.

“I was definitely tired, but I was excited for this year,” he said. “I think we’re all hungry to get a chance at the Astros again.”