Though the pitch has been around for nearly than 40 years, Jacob Faria's teammates implore him to keep the details of his best offering close to his vest. You can find the general blueprint online, in books and within wonkier, more creative pitching circles. But like a magician's trick or a grandma's secret recipe, there are things Faria can just do to his split-finger changeup that are more or less unteachable that make it different, and that render the intricacies of it worth protecting.
"Don't give away the grip!" Rays ace Chris Archer begs Faria from the corner of the clubhouse when a reporter asks to see how the young right-hander holds his split-change.
Archer is half-joking, but who could blame him if he weren't? It's the relative anonymity of Faria, and the mystery behind his best pitch -- colloquially nicknamed a "fosh" changeup, which is inside baseball talk for "Vulcan change," that mystical sub-genus of Wiffle ball whippers -- that has turned the 24-year-old into the American League's most effective rookie starter. And hitters' continued bafflement with Faria's unusual weapon could go a long way toward shaping the AL Wild Card race.
"I feel like it's really what has propelled me to the big leagues," said Faria. "As soon as I threw it for the first time, I thought, 'This is awesome.' It was so comfortable."
Gif: Faria's fosh changeup vs. a righty
Batters cannot say the same about facing Faria -- who starts Wednesday against the Blue Jays -- since he debuted in June. Besides a mostly unlucky outing last time, he has impressed by moving feet and missing barrels to the tune of a 3.19 ERA and more than six innings per start over 12 games. Without Aaron Judge in the picture, Faria would be inspiring some serious AL Rookie of the Year Award consideration.
At the root of Faria's success is the fosh change, which he learned on a lark on the last day of the season in 2014. Faria was 20 then, already a fourth-year pro and starting for Tampa's Class A affiliate in Bowling Green (Ky.).
"I just completely lost my changeup," said Faria, who threw a more traditional circle change at the time. "So I told my catcher, 'Hey I'm going to throw the split, so if it does something funky, that's what it is.' At the end of the game, I threw a bunch of good splits and my coach asked how I fixed my changeup. 'I stopped throwing it,' I said. In my next bullpen [session], I started throwing the fosh."
Statcast™ tells us that Faria's split-change is very, very good:

Now Faria throws it more than any other breaking pitch with two strikes, 28.7 percent of the time, as tracked by Statcast™. The pitch garners swings-and-misses 45.2 percent of the time, an elite rate. In 12 starts, Faria has allowed just six hard-hit balls off the pitch. Overall, his split-change induces an average exit velocity of just 78.6 mph, meaning it results in the second-softest contact of any starter's changeup in the Majors.
Faria grips the pitch unlike almost any other changeup in the Majors.
"Its just so much easier for me to throw off my fastball," Faria said. "They play off each other so well. The grip is what does it all."
Faria's particular variation involves him swallowing the baseball in his palm and spreading his index and middle fingers. That's the "split" part. The "change" part comes with his other three fingers; his ring and pinkie are wrapped along the far side of the ball, and his thumb is pushed high along the near side, pressed up against his pointer.
"Guys with smaller hands, I don't even bother showing it to them," Faria said. "With my old changeup, all my fingers were either on top or on the side of the ball."
The result is a screwball of sorts, a pitch that tumbles down and arm-side from a cold stopping point, giving the fall a vicious down and diagonal angle. When it's at its best, the pitch masquerades for what feels like seconds as a strike, only to pull back, almost teasingly, like a yo-yo or a person testing his toes in a cold pool.
Gif: Faria's changeup vs. a lefty
The fosh has lived in a constant state of prosperous scarcity since Orioles hurler Mike Boddicker introduced -- and named -- it at the Major League level in the 1980s. The pitch never died out completely, even as split-fingered grips as a whole fell out of favor over the past two decades due to health concerns. But the fosh is still rare. It's never been easy to teach or popular to throw, basically because there isn't really a standard way to throw one. Legendary O's manager Earl Weaver famously called Boddicker's "a cross between a fastball and a dead fish."
Faria is part of a small fraternity of current big leaguers to throw the fosh, a growing group that includes Kevin Gausman, Sonny Gray and Faria's teammates Jake Odorizzi and Alex Cobb. Each player grips the pitch a smidge differently, which stems a fraternity-wide reticence toward revealing their specific iterations. Faria described his, but did not allow photos.
"Some guys around the league still throw them," said Rays manager Kevin Cash.
But few warrant the fanfare of, say, Clayton Kershaw's curveball, Max Scherzer's slider or Noah Syndergaard's four-seamer.
Tom Gordon and Roger Clemens used the fosh in the 1990s. The last really high-profile starters to do so were Roy Halladay and Timothy Lincecum. Each employed his own variation in terms of grip.
Faria feels comfortable with his particular, uncomfortable-looking grip because, unlike many prospects, Faria threw a split-fingered fastball growing up in Southern California. The Rays scrapped the pitch from his repertoire after drafting him in the 10th round in 2011, for fear it would hurt his elbow. When Faria returned for his age-21 season in 2015, he did so committed to the fosh. And he flourished, going 17-4 with a 1.92 ERA across two Minor League levels. Less than two years later, Faria has grown into a fixture in Tampa Bay's rotation, thriving despite his secret slowing getting out.
"A lot of guys grew up with the thought that you can't throw anything that splits until you're older or your arm will blow up," Faria said. "It works. Once [the Rays] saw it, they were like, 'It's cool with us.'"