New splitter a ‘game-changer’ for Bryce Miller and the Mariners

From the beginning, nothing about Bryce Miller’s newest pitch has been subtle.

The Mariners’ 25-year-old right-hander has been openly promoting the development of his new split-finger fastball since December, posting slow-motion videos and spin-rate data on his social-media account weekly during the final two months of the offseason.

Miller did just about everything except buy billboard space outside T-Mobile Park reading: HERE’S MY NEW SPLITTER, HITTER; SEE IF YOU CAN HIT IT.

And in his first four starts of the season, nothing has been subtle about the early returns on Miller’s splitter: It’s real, and it’s glorious.

“The level of complication with this pitch, and then how quickly he’s done it — that’s unique,” said Trent Blank, the Mariners pitching strategist.

We’re still working from a small sample size here, to be sure, but the confidence Miller has developed in the splitter has been perhaps the biggest factor in his hot start, which included another gem on Wednesday in the Mariners’ 5-1 victory over the Cincinnati Reds.

Through his first four outings, Miller has a 3-1 record, a 1.85 ERA and 24 strikeouts in 24.1 innings, and he’s allowed a mere three hits — all singles — on the 70 splitters he’s thrown.

“It’s a game-changer for him,” teammate Logan Gilbert said. “It’s very natural for him, and he seems very confident with it. His arsenal is really good already, and I love how much he’s incorporated it — it’s not just a one- or two-time thing. He’s going to it [regularly], and it’s just part of his game now.”

Miller added the splitter to his mix mostly to give him a better option to use against left-handed batters, who touched him up as a rookie last season to the tune of a .303 batting average and a .917 OPS.

The early returns could not be more encouraging: Miller has allowed only one hit (a single) on the 44 splitters he’s thrown to lefties across 14 plate appearances.

And of his 13 strikeouts against lefties, five have come with the splitter, one more than with his elite four-seam fastball.

Right-handed hitters haven’t fared much better against his splitter, and hitters overall are whiffing on 33.3% of their swings against it.

“It kind of has a mind of its own sometimes,” Miller said, “but I’ve been able to command it really well. So, I’m really happy with it and I think it’s opened up a lot of things for me [against] lefties and righties.”

In 2023, the sweeper was the trendy new pitch around the majors. This year, the splitter is the hot new thing, and the Mariners have taken to it about as well as any staff.

In 2021, there were 43 pitchers who utilized a splitter on at least 5% of their pitches, per MLB’s Statcast data. That number is up to 61 pitchers this season, with Miller (19.4%), Gilbert (16.5%) and George Kirby (8.9%) adopting it as a part of their repertoire.

Gilbert introduced his splitter early in 2023, and Kirby started throwing it midway through last season. They’ve both offered guidance and feedback as Miller has learned the pitch over the past few months.

“He’s definitely asked a lot of questions … and he’s commanding it pretty well, which has been impressive,” Kirby said.

Kirby is the sport’s premier control pitcher, and he has perhaps greater “feel,” as they say, for his pitches than any other pitcher in the game right now. But he struggled initially last year to gain confidence in the splitter because it’s inherently a pitch that’s unpredictable; it’s a challenge to control, more challenging to master, and those elements are effectively the antithesis of who Kirby is as a pitcher.

“When I started throwing that pitch, it was so hard to understand — not like what it was supposed to do, but I couldn’t understand what I was feeling at first,” Kirby said.

Once he stopped trying so much to manipulate the splitter, that’s when his confidence and his effectiveness with it took off.

Now, Kirby said, “I love it. It’s just a good pitch that I can get below the zone with. It’s deceptive. As long as you’re throwing it from the same [arm] slot and throwing it just like the heater, it’s a hard pitch for hitters to have an approach to.”

Gilbert went through the same process in his development of the splitter.

“It’s going to be unpredictable by nature, and that’s something I’ve learned to accept,” Gilbert said. “It’s better when I treat it that way. My other pitches, I know what they’re doing and how to make it do what it’s doing. My splitter, I’m just going to throw it fast and let it do whatever it’s going to do. That freedom lets me just let it go. It’s hard to hit, it’s unpredictable, and I just want to keep it that way.”