Which pitch would each Mariners hurler 'steal' from a teammate?

May 14th, 2024

This story was excerpted from Daniel Kramer’s Mariners Beat newsletter. To read the full newsletter, click here. And subscribe to get it regularly in your inbox.

SEATTLE -- The Mariners’ rotation hasn’t just been among MLB’s most consistent. Their starting five has also featured some of the best pure stuff in the game. And each guy does it differently.

With that in mind, MLB.com recently polled Seattle’s starters on which pitch they’d most want to mimic -- or steal -- from a rotation mate, a query originally posed a few years ago from friend of the newsletter and former MLB.com colleague Corey Brock.

What he throws: Four-seam fastball (47.7% usage), slider (24.9%), sinker/two-seamer (14.6%), changeup (12.9%)
What he’d steal: George Kirby’s curveball

Castillo tried throwing a curveball in the lower Minors before the Reds quickly encouraged him to focus on his changeup instead. He marvels at how regularly Kirby’s curveball misses bats (with a 38.5% whiff rate) and that it’s basically a back-pocket weapon since he doesn’t use it as regularly.

“George's curveball, it's got a lot of movement, and if I could practice a pitch for whatever I have left in my career, I think it would be a pitch like that,” said Castillo. “I think for me, it's a little different just because my arm slot is about three-quarters. But Kirby throws overhand, so I think it's easier for him.”

What he throws: Four-seamer (41.4%), sinker/two-seamer (20.9%), slider (19.6%), splitter (9.9%), knuckle-curve (8.1%)
What he’d steal: Castillo’s changeup

Aside from Kirby possessing the best command among the rotation, his ability to manipulate grips to create specific shapes has been touted by manager Scott Servais as the best he’s seen in decades of pro baseball. But the one pitch he struggled to master was the changeup, which motivated him to ditch it altogether and add a similarly profiled splitter last season. That’s why Kirby admires Castillo’s changeup so much.

“It just looks exactly like his heater every time and just drops off the table,” said Kirby. “Just watching it in bullpen [sessions], it's like zero [inches of horizontal movement] and 22 [inches vertical]. I couldn't even create that if I wanted to.”

What he throws: Four-seamer (31%), slider (29.3%), cutter (19.1%), splitter (13.5%), curveball (6.3%)
What he’d steal: Castillo’s two-seamer

Gilbert is a totally different pitcher today than the fastball-reliant one that debuted in 2021. He retooled his slider ahead of 2022, added a splitter to great success last year and installed a cutter recently that has become a plus weapon. Yet, his delivery isn’t conducive to a two-seamer.

“You're kind of at the mercy of your slot a little bit, and whether you're coming through supinated or pronated,” said Gilbert. “People have different preferences [with] how their body works naturally. And from what I understand, my body just doesn't really line up that way, so it's kind of a long shot for me.”

What he throws: Four-seamer (45.0%), sinker/two-seamer (20.2%), splitter (18.1%), sweeper (9.5%), slider (7.2%)
What he’d steal: Gilbert’s cutter

Technically, Miller has already created his own version of a pitch that Gilbert mastered -- the splitter that he added last offseason. And he hinted that the cutter could soon follow.

“Pretty much how it's gone so far, he's a year or two ahead of me,” Miller said of Gilbert. “So whenever he finds a pitch, I let him prove that it works and then I steal it. I've kind of already started messing with [my own cutter]. I was going to wait until the offseason to mess with it. I throw like two a day in catch play to get a feel with it, then one or two in the bullpen. ... I have some natural cut, so I feel like it should be a pretty easy pitch for me.”

What he throws (2023 usage due to delayed '24 debut): Four-seamer (46.9%), sinker/two-seamer (25.5%), slider (15.1%), sweeper (8.8%), changeup (3.7%)
What he’d steal: Castillo’s changeup

Woo intends to use his offspeed stuff more regularly this year against lefties, after they tagged him for a .928 OPS his rookie year.

“I think, aesthetically, a good changeup is always fun to watch,” said Woo. “It's fun to throw, if you can throw good ones and consistently throw them. I think maybe it's just [about] me never being able to throw a good changeup. And [Castillo] has been doing it for so long. ... He makes it look so much easier, and if you talk to everybody else about throwing a circle-change, it's literally one of the hardest things to be able to do.”