Why the splitter could flip from baseball taboo to popular experiment for MLB pitchers

Here comes the pitch, and … freeze it there. Pause for a second. At this instant, the moment a pitcher releases the baseball, a path has been chosen, and the ball is about to embark on it. The pitch could be a fastball. It could be an increasingly common breaking ball, such as a slider, a sweeper or a curveball. It could be a changeup. Or it could be a split-finger fastball, commonly known as a splitter.

Despite the name, splitters are fastballs only in the sense that they mimic the arm action and initial flight of fastballs before revealing themselves as a type of turbocharged changeup, spinning less and diving more dramatically after pulling off the ruse.

If you’re cheering for the pitching team at this moment of release, a splitter gives you a better chance of being happy with the result of the next half-second than any other pitch choice in 2023. MLB hitters are managing just a .191/.232/.285 slash line, or a .517 OPS, against splitters. That makes the pitch noticeably more effective than the slider (.651 OPS), sweeper (.635 OPS), curveball (.647 OPS) or garden-variety changeup (.669).

Yet despite being a staple of arsenals in Japan’s NPB — the second-best professional league in the world — the splitter represents only 2.1% of pitches thrown in MLB in 2023. It’s a rarity forged by a generation of coaches and teams discouraging pitchers from trying it due to injury concerns.

That seemingly minuscule 2023 usage rate would nonetheless mark an all-time high for the splitter since pitch tracking data began in 2008. What’s more, Chris Langin, director of pitching at the influential Driveline Baseball facility, thinks there is plenty of room for growth.

“In the States, there's a taboo associated with it, and the frequency of classified splitters is just remarkably low,” Langin told Yahoo Sports. “And when you look at the performance of the pitch, it really doesn't make a whole lot of sense.”

As ever in modern baseball, the potential market inefficiency is drawing attention. Young starters such as the Minnesota Twins’ Joe Ryan and Seattle Mariners’ Logan Gilbert have added splitters this season, the Texas Rangers’ Nathan Eovaldi is dominating while throwing his more than ever, and the Baltimore Orioles have learned to win again with closer Felix Bautista making the splitter his signature out pitch.

Oh, and Shohei Ohtani throws one. So if this sounds like the beginning of a new pitching fad, a la the sweeper that so many pitchers added last year and that has recently become recognized as a distinct pitch classification, it has some of the signs. The Athletic sounded the siren about the splitter surge earlier this season, as an aftershock from or perhaps a sequel to the sweeper boom.

That said, a new splitter renaissance can’t be declared quite yet, but its mere possibility hints at the myth-busting, career-altering potential of the individualized player development and pitch design practices taking root in clubhouses and training facilities around the country. To understand why this pitch now defies easy dismissal after decades of decline, you have to understand how the taboo came to be and how much information goes into each and every choice before that baseball leaves the pitcher's hand.

Splitter seesaw: From savior to injury taboo to market inefficiency

If you look purely at the performance of splitters, the relative dearth of them in the majors is indeed puzzling. That owes to the history of the pitch, which features a complicated cycle of widespread embrace and reflexive shunning.

Hall of Famer Bruce Sutter, the game-changing closer, relied on his splitter as much as Mariano Rivera would later do with his cutter. He credited the pitch, thrown by wedging the ball between the index and middle fingers, for his success to an almost absurd degree.

"If it wasn't for that pitch, I'd be back in Pennsylvania working in a printer's shop,” Sutter told Sports Illustrated in 1986, as people around the game proclaimed the splitter the “pitch of the ‘80s.”

Some combination of Sutter, Oakland Athletics star Dave Stewart and San Francisco Giants manager Roger Craig — who died Sunday at the age of 93 — launched the splitter to soaring levels of popularity that lasted into the early 1990s. We don’t have pitch-specific numbers from those days, but the late San Diego Padres legend Tony Gwynn identified it as the rare nemesis that challenged his otherworldly bat.

“The splitter was the single most difficult pitch for me to hit during my career,” Gwynn once wrote for ESPN. “To hit a splitter, the hardest part was recognizing what it does. I always looked first for movement. It's tough to adjust to a ball that comes out hard and suddenly drops. How am I supposed to track that pitch with my bat?”

Even so, a rapid fall from favor ensued after Craig’s splitter-reliant Giants staff suffered a rash of injuries and conventional wisdom pointed the finger at the pitch. It’s not as if eliminating the splitter slowed down arm injuries, but the skepticism calcified. By 2011, industry sentiment had the pitch’s trajectory pointed more toward extinction than comeback — for reasons that sound particularly comical now.

"I always thought that, if thrown properly, with the fingers really split like a forkball, that's when you can get hurt because there's no resistance against the ball being thrown, and it really put a lot of pressure on the elbow," then-Tampa Bay Rays manager Joe Maddon told the Associated Press. "But it's not just about them getting hurt. They'll never develop their other pitches because they'll always get guys out with that pitch.”

Gee whiz, what a problem to have, right?

The prevailing philosophies today, by contrast, prize such devastating offerings and encourage pitchers to identify and utilize their best weapons. The detailed study of how to create those weapons — known as pitch design — has also moved beyond guesswork in some other important ways.

How baseball got a grip about splitter risks

Kevin Gausman, the Toronto Blue Jays’ All-Star who wields one of the game’s best and most used splitters, knows all about the old splitter stigma.

“When I was coming up, all anybody could talk about was how bad they thought it was for your arm,” he told Yahoo Sports. “You know, as a young pitcher, I was definitely told, like, ‘Don't throw it that much. Be really careful when you throw this. This isn't a pitch we want to throw that often.’”

Like any pitch thrown with the vigor of major-league competition, the splitter comes with injury risk, but actual research — in the stead of anecdotal evidence — hasn’t turned up any solid reason to believe it’s greater than that of other pitches. It’s simply different.

Craig, the proselytizing Giants coach, used to claim that the splitter was better for the arm because it didn’t require twisting of the wrist and elbow. That’s not exactly true, either. The splitter doesn’t demand the same twisting, but it can put extra pressure on crucial muscle groups and ligaments because of how a pitcher must spread his fingers around the sides of the ball to achieve the desired effect.

Recent pitching scholars have delved far deeper into the biomechanics of the kinetic chain required to hurl baseballs at elite levels. Tyler Zombro, an instructor at the cutting edge performance lab Tread Athletics and a pitcher on the comeback trail himself, pointed specifically to the elbow-adjacent muscles in the forearm that share responsibilities (and often concerning injury headlines) with the ulnar collateral ligament that famously leads to Tommy John surgery when it gives way.

“Obviously, if you split your fingers to a certain point,” Zombro said, “you can kind of feel that pretension on your flexor bundle.”

The unusual nature of the grip also leads to another worry about the splitter: inherent inconsistency in terms of movement and command. And that can be true, especially for those deploying it sparingly, but others, such as Gausman, have found it possible to wrangle the splitter with repetition — “the more you do anything, the more you're gonna do better at it,” he said.

Gausman takes specific, proactive measures to prepare his body to fling his signature pitch more than 38% of the time, tops among starters with splitters in 2023, working between each start to protect his elbow and even the fingertips affected at release.

“And just the older that I've got,” he said, “the more I understand that my prehab and all the things that I do to be ready for a game kind of help me to knock some of those thoughts out of my mind.”

One other reason you might be seeing more splitters? Most pitchers throwing them today don’t actually employ the most taxing form of grip — and no longer fear organizational backlash for declaring them splitters. Philadelphia Phillies right-hander Taijuan Walker, who has used the pitch throughout his career, said he considers his version a split-change hybrid, a type of grip plenty of pitchers might’ve passed off as a changeup in the days when many organizations forbade throwing a splitter.

“Mine doesn't really slip out like a true splitter does, you know, it has kind of some two-seam rotation to it,” Walker said, referring to the way the ball comes spinning off his fingers instead of popping out of the gap like a knuckleball. “So I think when I throw mine — and having bigger hands helped, too — I don't think it puts that much stress on my arm.”

These days, there are three main ways to grip a splitter:

• The split-change grip, sometimes known as a “fosh” grip, is the least demanding on the fingers. The pitch’s proliferation, if it continues, is likely to be heavy on these. Gausman, for example, puts his ring finger on the side of the ball along with his middle finger and throws it like a fastball. He allows the ball to roll off his middle finger, and “it actually kind of spins like a lefty slider,” he said.

• A regular splitter grip, for lack of a better term, involves only the index and middle fingers and the thumb. Langin, the Driveline pitching director, described the process of positioning the ball in this one as a “placement” between the two fingers, not a jam. He said most pitchers can make this style work, regardless of their finger length and capacity for stretching.

• Forkball grips are the most extreme and least common in the majors. This is a version of the grip in which the pitcher totally lodges the ball into the pocket between his index and middle fingers and releases it with very little spin, providing more of a velocity difference and a touch of the fluttering flight of a knuckleball. Only hurlers with particularly large hands are likely to pull this off, and even then, it can be difficult to control consistently.

There’s general confusion, accentuated by New York Mets rookie Kodai Senga’s “ghost fork,” around the forkball vs. splitter distinction, but in the contemporary game, the pitches are synonymous, and any difference is largely in how the pitch gets thrown. Langin pointed to Gilbert — the Mariners starter who added a splitter this offseason — as a rare pitcher who’s capable of using the forkball-style grip.

“Gilbert has probably the biggest hands I've ever seen for a pitcher,” Langin said. “It's actually absurd.

“Generally that forkball, that wide one, is not something you go to right away, for a variety of reasons. But with him, it was just, like, this is gonna feel like a golf ball in his hands still, so he kind of has the capacity to do that and not suffer with command.”

What has become clear to Gausman — especially with Ohtani’s splitter popping up as a frequent star of strikeout GIFs — is the rising interest in giving the pitch a try.

“That's usually the first thing any pitcher, young pitcher or older pitcher, wants to ask me,” Gausman said. “‘Show me the grip.’”

Which MLB pitchers could add splitters?

Not everyone should rush out and add a splitter, just as not everyone needs to tinker with a sweeper.

“There are definitely buzzworthy pitches that kind of blast on the scene, and then everybody's chasing after that movement profile,” Zombro, the Tread instructor, said.

In helping pitchers improve or sometimes rewire their arsenals, Zombro tries to focus on what pitches make sense for each pitcher based on individual characteristics. These days, those go way beyond lefty or righty. Professional pitchers are increasingly aware of and talking about their natural motor preferences — the way their arm chucks baseballs when left to its own devices, the way they feel most comfortable imparting spin.

Are you a natural pronator? Or a natural supinator?

(If you hold your arm straight out in front of you, pronation is the movement that would point your thumb down and your palm outward. Supination is the movement that would leave your thumb pointing up and your palm pointing inward. It’s the motion of a karate chop or throwing a football.)

“Everybody pretty much has a preference,” Zombro said, noting that it’s usually apparent from a few max-effort throws or warm-up exercises. “And then, it's identify the preference, don't necessarily try to overhaul them [or] change them out of it, but maximize what they've got.”

This knowledge can be crucial for pitchers, steering them toward their strengths or even providing a fresh start after they spend time pursuing modes of operation that might’ve been en vogue but were out of touch with their bodies.

Generally, being a natural pronator is the best ticket to throwing a good, traditional changeup. Pronation is what’s happening when Milwaukee Brewers reliever Devin Williams releases the most devastating traditional changeup in the sport, with the ball seeming to fly off the pinky side with his hand tilted outward.

The vast majority of professional pitchers, however, are supinators.

“If you're looking at the highest levels of baseball,” Zombro said, “odds are they're gonna be supinators because there's a lot more avenues to success that way.”

Namely, natural supinators tend to have an easier time throwing a wide range of breaking balls and throwing them at higher velocities. Anyone familiar with Jacob deGrom’s 92 mph sliders can get the gist of why that’s a good thing. Granted, pitchers have to do both motions at various points, but many supinators have trouble developing good changeups, which means there’s a market for a pitch such as the splitter.

Why? For a supinator, a splitter is a changeup that can be achieved mostly through the grip and thrown with a fastball motion that doesn’t rely on the extreme pronation that might be uncomfortable or impossible for them.

“So it's not necessarily that those people have to throw a splitter,” Langin said, “but I would say the guys who supinate just should not be trying to turn over the changeup Devin Williams-style.”

And from a strategy perspective, splitters don’t have a platoon problem, whereas the breaking pitches at which supinators excel tend to perform worse against opposite-handed hitters. The old rule that pitchers needed to develop changeups to remain starters stemmed from this issue. And while that rule has been broken by some of this generation’s legends, the thrust of it stands for most of the pitching population.

Baltimore Orioles GM Mike Elias identified the splitter’s neutral platoon numbers as a plus when considering relievers, such as his closer, who use the pitch. And it’s safe to say the organization is not discouraging splitter development.

“If a guy has one and it's good, great,” Elias said. “We've never had big conversations out of the ordinary about splitters. I mean, we're very happy we've got Felix Bautista right now.”

At Driveline, Langin identifies splitter candidates as natural supinators or pitchers with over-the-top arm angles who struggle to achieve side spin. Within that, his group works to more finely categorize grips and deliveries to match pitchers with the options most likely to suit their biomechanics. This season, he has an excellent example in Ryan, the young Twins star and a natural supinator who added a splitter this winter. Ryan is throwing the pitch more than a quarter of the time this season. So far, it’s allowing just a .179 batting average and has accounted for 20 strikeouts.

Langin’s theory holds that there are more pitchers whose natural inclinations point to the splitter as a good option, perhaps even a career-changing one, if they are willing to put the ‘90s injury warnings out of mind.

“I think we're probably failing some people,” Langin said, “by basically revoking from them the opportunity of throwing — or at least potentially learning — a splitter.”