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The Science Behind Josh Hader's Fastball: Why It's Unique and Defies Classification

Angle. When you look at Josh Hader, sharp, precise angles come to mind. He brings his front knee back into an extremely drawn position and then unleashes a series of wild angles on the batter – hair, elbows, wrists and then the legs with a final whirl and kick – to create a fastball aimed at the Batsmen exploded. So perhaps it's no surprise that the second-most valuable sinker in the major leagues over the last eight years benefits from all sorts of effects best described by geometry and physics.

Wait, sinker? Ranked in the top 10 of all fastballs in the major leagues, is this pitch a sinker?

“I think of it like a fastball,” the lefty said with a laugh.

“I look at it as a riding fastball,” his pitching coach Josh Miller said.

“To be honest, one of our pitching coaches told me last year at LA that it was a tackle and I had no idea. I thought, 'Oh, I thought he only hit a four?'” new teammate Jason Heyward said. “But when I look at it more closely lately and just see the angle he throws it at, I can see why you would call it a two-seam. But I had no idea it was a double stitch. I thought it was always a foursome that had the height.”

If it moves like a four-seater, why is it a sinker? Because he clutches it like a plumb bob. Here's a video from Lance Brozdowski where you can see that Hader clearly has his fingers along the seams rather than across like you would on a four seam.

So Hader throws it in one direction (with a sinker grip), but the throw moves in a different direction (like a real four-seater). How is that possible? The subtleties of spin might have something to do with it. Many true sinker throwers use a seam-offset caster line to create downward and arm-side motion in their throw. Clay Holmes is one of those pitchers. He throws to the right, but he spins the ball about the same amount as Hader, the speed is similar, and even the axis around which the ball spins is similar. But Holmes gets a whopping 15 inches more sink on his sinker.

The reason may be that if you look at the way Holmes' sinker spins, you can see that the seams on the left side of the ball are tightening. A continuous seam along one side of the ball creates the wake in a “seam-shifted wake.” This suction pulls the ball toward Holmes' arm side and destroys the “ride” effect on the pitch, giving it a super-drop sinker. As Trevor May pointed out on the Rates & Barrels podcast this year, Hader's ball spins without seams forming on either side. This 'wobble' in the spin means there is almost no seam shifting caster effect and no reduction in ride quality that normally characterizes a four seater.

He deceives by creating a gap between the way the ball is gripped and the way it spins, but there's more, and it has to do with his arm angle.

Hader and Drew Smyly have the same pivot on their sinkers but very different arm slots. Only 12 qualified lefties have a higher arm angle than Smyly and only 21 qualified lefties have a lower arm angle than Hader, which we can see thanks to BaseballSavant's new arm angle leaderboards. These two throwers have the same axis of rotation, but look at how different the arm angles are.

Because of the slot in the forearm, hitters expect a certain type of movement. The movement you would see from a sidearmer, especially one throwing a sinker – balls that have a lot of drop and fade. Instead, you get a ball with tremendous running feel. This discrepancy between what is expected from the arm slot and what actually arrives at the plate is important to the pitcher, and the Astros have capitalized on it before.

“I would say it’s similar to Cristian Javier’s fastball conundrum a few years ago,” Miller said. “Guys aren’t used to seeing that. You're not used to seeing the low slot with the vertical component on Velo. Batsmen aren’t used to that.”

Here is a graphic from Max Bay's model showing the expected movement of the pitcher's arm slot (in the concentric blue circles, with the center being the most common) and the pitcher's actual movement (in the orange circle, which represents the majority of his throws). . for Javier. Batters expect that dark blue because that's what they normally get from that arm angle, and instead they get the orange from Javier that “jumps out” at them and causes all sorts of problems.

It doesn't matter at this point what you call Hader's pitch. Call it a four-seater, and Hader gets nearly 5 inches more drive than you'd expect given his arm angle, which would be the widest among four-seaters in baseball. Javier would be second on this list.

How does the left-hander manage this deceptive ride from his low perch?

“I try to stay on the ball so my hand position changes, and that cue helps me master the fastball,” Hader said in 2019.

It's this hand position that allows him to achieve the same axis of rotation as Smyly from such a different slot, but larger cues are also important for the pitcher.

“As long as I don’t go sideways. With my application, early in my career, I tended to go from west to east rather than north to south,” he said this year. “That would be the greatest thing.”

Also Where He throws the ball, that's a bit important.

“When he throws it in the top half of the zone, it’s really good,” Miller said. “He has a unique delivery that I don't think we would teach, but it works for him. “We just have to push it as far up the zone as we can and let it play.”

By keeping his energy in tune with the plate, focusing on staying with his hand on top of the ball and throwing high into the zone, Hader is able to throw a great fastball out of a sidearm slot. All in all, it's really intimidating. It has the highest whiff rate of any sinker (at least 150 whiffs) in the last four years, a whopping 5 percentage points above second place. Even if you include the four-seaters again, only Mason Miller and Jhoan Duran have higher whiff rates on their heaters during this period. The .184 batting average against his reliever is the best in the game over that span (minimum 1,000 pitches), just ahead of Tarik Skubal. It's a great place.

Here's what it looks like from the hitter's perspective, thanks to video from Eric Longenhagen at FanGraphs, with overlaid graphics to highlight the unique qualities of Hader's fastball.

Why does Hader think the pitch works so well for him?

“My opponent’s deception is that they won’t get the ball until later,” he said. “I think it's more of a deception than the actual pitch. Obviously it's a unicorn pitch, but I don't think the pitch is the all-in-one special. I think it’s the deception that helps the fastball game get a little bit better.”

And he's right. It's about the deceptive angles he creates – the arm, the hand and the turn.

(Illustration by Dan Goldfarb / The athlete; Photo: Joe Robbins / Icon Sportswire via Getty Images)
(Graphics by Drew Jordan)

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