Jake Diekman and Griffin Jax on Learning and Developing Their Sliders

Bob DeChiara-USA TODAY Sports

The Learning and Developing a Pitch series is back for another season, and once again we’ll be hearing from pitchers on a notable weapon in their arsenal. Today’s installment features a veteran left-hander, Jake Diekman, and a young right-hander, Griffin Jax, on their signature sliders.


Jake Diekman, Boston Red Sox

“I learned a slider in my first year of college, or maybe in my senior year of high school. It was my breaking ball. If you’re under 16 years old, you should not throw a curveball or slider. That’s my opinion. You should just develop a heater — maybe a two-seamer — and a changeup.

“When I started [throwing a breaking ball], I threw it from over-the-top. It was curveball/slider-ish. When you’re 18 years old — this was back in 2005 — no one really gave a care if it was… I mean, we just saw it break. It was, ‘Oh yeah, that’s a breaking ball.’ Now they classify [pitches]. And there are sliders that look like curveballs, and sliders that look like cutters.

“My slider two years ago is different from any slider I’ve ever thrown. You just evolve. Sometimes you’ll keep the same slider for three, four years in a row, and then you start throwing it in spring training or in the offseason and you’re like, ‘I don’t know how to throw this thing anymore.’ You have to find a different seam, different thumb placement, a different whatever.

Jake Diekman’s slider grip.

“The feel of it… it has to feel somewhat right in your hand. It’s a really weird thing. I don’t know if you can explain it to a normal person, but for a pitcher it’s like, ‘Man, I lost the feel for this, I lost the feel for that.’ And then you change a little something and it feels identical. You’re like, ‘Oh, all right.’

“I don’t work with the camera so much, like with hand placement. If I can see it spin right on a Rapsodo, or I can get the spin rate and spin axis, I can go off that pretty well. [Compared to two or three years ago], I throw it off a different seam. My thumb is on a different area of the ball. It’s on a seam. It’s right on the horseshoe, on the bottom. And then I also spike it a little bit.

“I don’t [preset my wrist], but that’s what I come set with. If you’re a young pitcher, you should learn how to grip your hardest pitch [to throw] while you’re getting stopped. You shouldn’t go from a heater to your hardest pitch, because you’re moving your hands too much and hitters can pick up on that. Grip the pitch that’s hardest for you to get in your glove. For me it’s the slider, because I spike it a little bit.

“I dropped my arm angle in 2009 — I had to get my head out of the way — to like low three-quarters. I had to learn a completely different pitch mix. My slider profile, when I first got called up in 2012, was completely different than it is now. It spun probably not as good as it does now, axis-wise, to complement my heater. It had more depth — it was more like a slurvy pitch — and the velo was also higher. I threw harder then. I’m not as young anymore.”


Griffin Jax, Minnesota Twins

“The pitch I’m most known for is my slider. Analytically. it ranks pretty highly in MLB. It’s a funny story, actually. I was at the alt site last year, right after spring training, and we’d throw live batting practice and live sim games, but we wouldn’t have a defense behind us. It would just be the pitcher and the catcher, with four or five guys rotating in and out to hit.

“I was facing Trevor Larnach, Alex Kirilloff, Nick Gordon — some of our younger guys — every time I was on the mound. I was throwing fastball/changeup/curveball, like I’ve done my entire life. Maybe the seventh time they faced me, I wanted to show something different. I was toying around in catch-play, right before I was about to go on the mound, and was like, ‘What if I just turned my curveball a little bit?’ That’s how I got the slider I have now.

“The coaches were like, ‘What did you just throw?’ I said that I was just kind of messing around and that I was supposed to be throwing a slider. They said, ‘Yeah, throw that again.’ We just continued working on it, working on it, and got to the point where I can throw it comfortably and confidently. Now it’s my lean-on, pretty much every time I’m out there.

“I’d thrown a slider hybrid in college, but it wasn’t very good. I was fastball/changeup in college — those were my main pitches — and then I had kind of a show me-slider that I would never throw for strikeouts. Once I got into the Twins organization, the priority for my development was learning a slider or a curveball — some kind of breaking ball. I found a good curveball grip that I’ve been leaning on for a little bit, and then at the alt site I found that slider, which kind of took off from there.

“When we look at pitchers nowadays, you kind of put them in two categories. You put them in either as a north-south guy — like a carry guy — or you put them in as an east-west sinker guy. My fastball/curveball profile is in the north-south — fastball at the top of the zone, curveball at the bottom — and my slider is pretty much pure east-west. When you’re showing a scouting report on a pitcher… for me, they’re looking primarily top-of-the-zone, bottom-of-the-zone. But when I’m able to throw my slider to the side, off the plate to righties and in to lefties, it’s a completely different movement than what they’re expecting. My slider is more sweepy. It has very little depth. It’s almost all horizontal.

Griffin Jax’s slider grip.

“When I show people my slider grip, they kind of smirk, because it’s not ordinary. I’m kind of on that horseshoe. I put a lot of my pressure on my middle finger to rip that seam, and then I spike my index finger to help get some speed-kill. [The spin rate] ranges from about 2,800 to 3,000 [RPMs]. The spin, the direction, horizontal movement, all that stuff profiles pretty nicely.

“The way I kind of tell myself to throw it, across my body… it’s almost like I’m trying to throw it like a Frisbee, sidearm. That’s how it takes that shape. I spike my curveball, and like I was saying, I just started rotating my curveball grip a little bit to see if I could get… originally I wanted to still get some depth, but I wanted to get more horizontal, because my curveball is 12–6. I wasn’t expecting my slider to go completely the other way — the other way in a good way.”

David Laurila grew up in Michigan's Upper Peninsula and now writes about baseball from his home in Cambridge, Mass. He authored the Prospectus Q&A series at Baseball Prospectus from December 2006-May 2011 before being claimed off waivers by FanGraphs. He can be followed on Twitter @DavidLaurilaQA.

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2 months ago

I love this stuff. It’s fascinating to hear the players talk about their development. There’s so much more to baseball than just talent–you have to grow, adapt, and learn in order to succeed.