Demystifying Tyler Duffey's "Slider"

Mandatory Credit: Marilyn Indahl-USA TODAY Sports

PITCHf/x says Tyler Duffey throws a slider.

So does the board that lists pitch type and velocity at Target Field.

Depending on who you believe, Duffey throws the pitch about 12 percent of the time — a not insignificant amount when considering the rap on him as a starting pitcher is that he never developed a true third pitch.

But if you ask the player himself, nothing has changed.

Well, maybe not nothing — but not much.

“Not in my mind, at least,” Duffey told Zone Coverage when asked if he’s added a slider into his repertoire. “Maybe the way it’s coming out of my hand…maybe it plays as a slider. But in my mind, it’s the same grip — just different velocity. Whether I’m getting behind it more or over the front of it, maybe that’s the difference.”

That same grip is the knucklecurve, which has been Duffey’s bread-and-butter offering off his fastball since his MLB debut back in 2015.

“Yeah, it’s still the exact same pitch,” Duffey said. “From 75-86 mph or 87, whatever it was, it’s literally the same grip, I’m just trying to throw it harder. Last night it showed up as a slider. Cory (Provus) was asking about it too. I think last night it was spinning more like a slider.”

Basically, Duffey explained, he adds and subtracts to get the pitch to do different things — but it’s all with the same grip. So in his mind, it’s still the same pitch.

“Not particularly,” Duffey replied when asked if the pitch is shaped any differently based on which version he throws. “Obviously on the slower one, I have to throw it a certain way to get it over the plate. But increasing the velocity just shortens the movement. On paper, they’re all the same — like the plane that they’re on. Just the velocity changes.”

So while the amount of movement changes based on how he throws it — not unlike throwing a slider with more velocity and having it shorten into a cutter — Duffey doesn’t really buy into the idea that it’s a different pitch at all.

Sep 23, 2018; Oakland, CA, USA; Minnesota Twins catcher Chris Gimenez (46) fist bumps with Minnesota Twins relief pitcher Tyler Duffey (21) after getting Oakland Athletics designated hitter Khris Davis (not pictured) to pop out during the eighth inning at Oakland Coliseum. Mandatory Credit: Neville E. Guard-USA TODAY Sports

It is, however, important for Duffey to dictate which one he’s going to throw to his catchers. Catching a 75 mph pitch is quite different than catching one at 85, after all.

“I tell the catchers to go 2 (fingers down) if they want the softer one and 3 if they want the harder one,” Duffey said. “That way there’s a clear-cut difference so they know it’s coming, especially if I’m going to rip the hard one into the ground. I just get on the same page with them and I can still toy with it within that range.

“Sometimes with the curveball itself, the 75-80 (mph version), it’s all the same pitch. It just varies day-to-day. If one feels better, I’ll throw one more than the other. But at this point, we’re just mixing them up.”

The slower version, Duffey said, will sit in the mid-70s while the harder version creeps into the mid-80s.

Duffey stole the idea of a slower breaking ball from teammate Ryne Harper, who spent last year in Rochester with the Red Wings.

“I kind of did it when I was starting,” Duffey said. “Maybe not as drastically. But when I was in Triple-A in 2016 I think it was, I kind of messed with it. But last year with (Ryne) Harper, he was with us all year, I saw him do it and I was like, ‘I’m going to try to do that.’”

Duffey said he likes the ability to mess with hitters with a pitch that’s just so slow, they can’t help but either look at it or simply make bad contact.

“Yeah, so I started messing with the really slow breaker last year,” he said. “Just because I saw Harper doing it and it was so effective. It’s such a drastic change. So I started flipping those in there, and it’s worked.

“I’ve gotten some broken bats this year, some takes — more than swings — which is fine with me, because it’s like, “What was that?” So I can steal a strike or get back into a count sometimes. Basically, it’s three pitches for me, and the fastball is playing way better than it was.”

Hang on — three pitches? So not only is it not a slider, but it’s three pitches?

Duffey clarified by saying his old knucklecurve was the one that comes in around 77-80 mph, and he’s added and subtracted from it to mess with timing and get longer and shorter movement depending on the situation and how he’s feeling that day.

As one might expect, the varying of the pitch produces different results, as well.

“The harder velocity one that I’m throwing has produced a lot of swings and misses,” Duffey explained. The numbers bear this out, as well. According to PITCHf/x — housed on Fangraphs, Duffey has a stunning 29.4 percent swinging-strike rate on his ‘slider’.

A roughly average swinging-strike rate is 10 percent, though it’s lower for fastballs and higher for breaking balls. One can safely assume 15 percent and up is a good whiff rate on a breaking ball, with 20 percent and up in elite territory.

“They told me this spring that it plays better, so throw that one. Literally, I could throw it every pitch if I wanted to. I’m not going to do that. I like my arm to stay attached,” Duffey said with a wry smile. “I try and mix it up, but there are times when you have a good hitter and you’re going to throw him your best pitch no matter how many times it takes. I think not throwing it all the time also keeps it playing up to where it doesn’t lose its effectiveness, which is so huge.”

So maybe Duffey doesn’t throw a slider after all. But whatever he wants to call it, it’s working.

He hasn’t allowed a hit on it yet this season.

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