The Mystery New Pitch That’s Driving MLB Hitters Crazy

Arlington, Texas

Pittsburgh Pirates ace Paul Skenes has emerged as the best young pitcher in years thanks to a blazing fastball that hits triple digits on the radar gun, Jedi-like command and uncanny composure on the mound.

But one of the biggest reasons why batters have found him close to unhittable is a mysterious new pitch that’s so nasty it somehow defies classification in a game that has everything from slurves to screwballs.

It comes in at 94 mph, but is it a fastball? It has an off-speed grip, but is it a splitter? It drops like a rock, but is it a sinker?

Nope, it’s a “splinker.”

“I call it a sinker, everybody else calls it a splinker,” Skenes said Monday, before becoming the first rookie to start the All-Star Game since 1995. “That’s how I view it—having a different fastball, different shape, and [it] forces hitters to choose between one or the other.”

Skenes’s splinker comes in just a little slower than his 100 mph heater, but it nosedives like a splitter. He developed it with the intention of catching major-league hitters off guard—in the same way most pitchers use a change-up or other off-speed pitch—and so far, it’s done the job. In his 10 MLB starts so far, Skenes has thrown fewer than 1,000 pitches overall, but more than 300 of them have been splinkers, according to Baseball Prospectus.

One of the oddest things about the filthiest pitch in Skenes repertoire is that he discovered it entirely by chance. Last summer, not long after he was drafted No. 1 overall out of LSU, Skenes was working to develop a pitch that had rightward movement to pair with his primary fastball. During one throwing session, his grip slipped, causing the ball to come off his middle finger instead of his index finger, decreasing the spin of the pitch while maintaining its velocity.

“I just kind of discovered it on one random throw, and then I just kept doing it,” Skenes said. “How I was holding the ball didn’t change. But the way I was releasing it and what I was feeling as I released it changed a little bit.”

Just like that, Skenes’s splinker was born. One year on, it’s become his primary strikeout pitch.

That was only the latest in a long line of happy accidents that created the pitch that’s now taking over baseball. The original splinker belongs to Minnesota Twins reliever Jhoan Duran, who pretty much had the pitch to himself since his MLB debut in 2022.

Duran also wanted a fastball that had more rightward movement than his regular heater, but didn’t like the result he got with a traditional two-seam fastball grip. Instead, he tried to grip the ball like he would for a split-finger fastball, which produces less spin and typically less velocity.

“I tried in the game, and I saw the way it moved,” Duran recalled. “I said, ‘Oh my goodness.’”

Hitters aren’t the only ones who have been bamboozled by the splinker. The same goes for the people whose job is to classify pitches.

Harry Pavlidis, the founder of pitching classification and data company Pitch Info, jumped into action as soon as Skenes began regularly throwing the pitch following his major-league debut in May. Pavlidis immediately added the splinker as a distinct category of pitch on Baseball Prospectus’ statistics page.

Though the pitch remains a mystery to most MLB pitchers—only six have thrown one in a game this season—Pavlidis is convinced it won’t stay that way for long. Baseball is a copycat game, after all. “As soon as I saw a couple more guys tinkering with it, I jumped into our system,” Pavlidis said. “Like, ‘Oh, it’s about to become a thing.’”

The history of the splinker really starts not with Skenes or Duran or any other MLB pitcher but with a mechanical engineer named Barton Smith, who published a scientific paper four years ago that presented a compelling theory on the movement of a baseball.

By then, pitchers had been throwing two-seam fastballs for decades. But finally, for the first time, there was an explanation of how and why it worked.

“When seams are in certain areas on the baseball’s surface the airflow changes,” the paper’s abstract says. So, the concept of “seam-shifted wake”—and a new way of understanding horizontal movement—was introduced to baseball.

The first big new development in this era was the “sweeper,” a sharply horizontal slider that seemingly every pitcher in the game began experimenting with in 2021 and 2022. But many pitchers throughout history have thrown sweeping sliders long before the theory of seam-shifted wake was made public. The difference became that finally, they could be reverse-engineered.

The splinker, a true hybrid pitch that combines the traits of two opposing pitch types (off-speed and fastball), might be something more than a new classification for an old pitch, Pavlidis says.

“There’s a lot that can still be done with pitch design and innovation in pitching,” he says. “We’re quite sure that there are opportunities for novel ideas about how a ball can move. Right now, you have five guys throwing a splinker. But this could be one of many new ideas in the realm of pitching.”

Write to Lindsey Adler at [email protected]