The Mets Are Throwing the Dan Warthen Slider

Longtime Cardinal pitching coach Dave Duncan loves the sinker. The Braves’ Leo Mazzone was all about establishing the pitch low and away. Rick Peterson may hate the cutter.

The Mets’ Dan Warthen may not have the name value of legendary pitching coaches that have come before him, but he does have his own pitch. If you want to see what it looks like, you just have to notice how the Mets, as a team, are outliers when it comes to slider velocity and movement.

The Mets are throwing a different kind of slider.

Pointing out what this Mets slider is all about could be as easy as linking to this leaderboard, which shows that the Mets have the hardest sliders in baseball. Or even this leaderboard, which shows that Jacob deGrom, Matt Harvey, and Jeurys Familia are in the top 15 when it comes to slider velocity.

But that’s not enough, really. Because the Mets boast young flamethrowers who throw everything hard.

Instead, let’s focus on two aspects that control for overall velocity. The Mets look like outliers even when you look through the lens of fastball-slider velocity differential combined with vertical movement. A lower number means more drop, so you’ll see that the Mets have slightly less movement than average, while having a smaller differential between their slider and fastball velocities.

Maybe the Mets don’t look like they are all alone in this world now. The Astros and Rangers seem similar, at least. It’s when you start talking to the players — and Warthen himself — that you realize that he’s really got his own spin on this pitch.

Back in 2012, David Laurila spoke to Matt Harvey as an “emerging ace,” and Harvey heaped praise on his pitching coach for one pitch in particular. “Dan Warthen helped me out with the grip during Spring Training,” said Harvey. “I threw it last year, but I didn’t really know how to throw a slider.”

And in 2013, when Jenrry Mejia was reclaiming some of his promise, he deflected praise to his pitching coach when speaking to Andy Martino: “When I came here in September last year, Dan Warthen showed me how to throw a slider,” said a beaming Mejia, back in a major league clubhouse. “Then I threw it in winter ball. And now I throw it perfect.”

This year, Mejia told me once again how important that learning moment with Warthen was to him — “for sure, he helped me out so much” — and praised the ease of the slider. “Don’t think about it, just throw it, just throw it like a fastball.” Mejia’s slider, which isn’t included yet in these numbers, averages 86 according to the pitcher and 84 according to our boards.

That sounds very much like what Warthen told me was the key to the pitch. “It’s a different spin, it’s a different grip. The whole idea is not to use your wrist to try and spin the ball, you want your fingers to spin the ball. You’re thinking fastball and just kind of cutting through the ball,” he said before a game against the Giants.

Warthen has a disciple in this year’s closer, Jeurys Familia, too. The slider, which replaced his slurve, has “small, quick, movement at the end,” and Familia said he has “more command of it.” You throw it like a fastball, and “at the last point you just flick your fingers a little.” Sounds like a great pitch.

Take a look at Familia’s grip for his old slurve (left) and his new slider (right), and you might notice most the distance from his palm to the ball. This is a pitch that sits in the fingers more than the palm.

The slurve (left) was much deeper in the palm than the new slider (right).

Even the pitchers who haven’t thrown the Mets version of the slider yet are aware of the pitch. “I played with it a little bit to pick up the RPMs on my curveball,” admitted Noah Syndergaard, who has recently seen his spin rate on the curve drop precipitously even as the velocity on the pitch goes up. Thor saw his RPM drop from around 1500 earlier in the season to around 1000 in his last start. Jonah Pemstein’s work in these pages suggests that’s a good thing for the curve, and it was achieved through Warthen’s tutelage.

This clue, along with something Warthen said, might actually provide us with the way to spot the Mets’ slider in the numbers. “Tight spin, and we’ve gotten a lot of swings and misses,” Warthen said, referencing spin again. But, paired with Thor’s lowered spin rate, that spin is actually less than you’d expect from other sliders.

Take a look at spin versus velocity for this year’s slider-throwers, and there you go. It’s all Mets in the top left corner, with the highest velocity paired with the lowest spin rates. Hover over the top left and find most of the Warthen success stories. Hansel Robles!

Both Syndergaard and newcoming lefty Steven Matz — who isn’t learning the slider because the team wanted him to “focus on developing the curveball” — are interested in learning the pitch, and that’s no great surprise.

Maybe that’s because they can see what a success story deGrom has been. When I talked to deGrom last, he was in the midst of making his slider harder — “It’s been quite a bit harder than it has been” — but it was 87-88 then. It’s now 89 mph and the eighth-hardest slider in the bigs.

That’s deGrom’s old slider on the left, at 84 mph with a big break. That’s an 89 slider on the right.

Warthen said that deGrom was a little bit too obsessed with movement at first. “He was trying to make it break, and we don’t want to make it break, we want to think about getting our fingers to the front of the ball and spinning the baseball,” Warthen said of the pitcher on whom he may have had the greatest impact. “Then you take another breaking ball and you separate the speeds, and it doesn’t have to be a great breaking ball, it just has to be a different speed.”

Before deGrom upped the velocity on his slider, his curve got 10% whiffs and his slider got 9% whiffs. Since he started averaging 88-89 on the slider, his slider has gotten 13% whiffs — and his curve has jumped to 16%. His curve didn’t really change in shape. He just had a bigger differential between the pitches.

Considering that the cutter is faster and has less movement than your traditional slider, it’s fair to ask Warthen if he’s just teaching a cutter. “It’s not a cutter, because if you move your thumb up it gets bigger, if you move your thumb down, it gets smaller,” Warthen smiled. “You can regulate the spin on the baseball and the break on the baseball, and the velocity. You can spread the velocity just by moving your thumb.” You could also say that the average cutter drops more than four inches less than the average slider on his team.

Critics might point to arm injuries on the Mets as proof that the pitch is hard on the arm, but Warthen laughs that off. “It’s easy on the arm when done correctly, it’s not one of those pitches that you try to make break,” he said. And these pitchers all throw hard, and there is a relationship between just throwing hard and arm injury. It’s impossible to split those effects apart.

Ask Warthen if he’s in his dream job, and he doesn’t equivocate. “Absolutely. All of these guys are good guys, too, and they want to learn. Syndergaard and Matz and Harvey — they’re just sponges, and they want to learn.” That’s no surprise. You’d hope most pitchers would want to learn the low-spin, high-velocity, all-in-the-fingers slider that helped make Matt Harvey, Jacob deGrom, Jeurys Familia and Jenrry Mejia who they are today.

That’s a pitch good enough to get its own name: The Dan Warthen Slider.