Michael King, Lucas Luetge, and Jordan Romano on Learning and Developing Their Sliders

On hiatus since the onset of the COVID-19 pandemic, FanGraphs’ Learning and Developing a Pitch series returns with three pitchers — Michael King, Lucas Luetge, and Jordan Romano — telling the stories behind their sliders.

———

Michael King, New York Yankees

“I’ve been developing a slider since my freshman year of college. I was always bigger curveball, and then I had like seven different grips in college. I could never get consistent with anything — not consistent movement, not consistent location — and it just never felt comfortable. So I always used to say that I was a sinker/slider guy that didn’t have a slider.

“Once I got drafted in 2016, I said, ‘I don’t care what it does, I’m sticking with this grip so I can at least locate it.’ In 2018 is when I finally felt like I was consistent with the shape and the location. Then we got a new pitching director, Sam Briend, and he said, ‘Your slider is terrible. It’s located well, but it doesn’t have a good movement profile. Let’s fix it.’

“In 2019, I got hurt, and then it was the whole process of trying to change the movement profile. I wanted it to be more horizontal, more sweepy, like [Corey] Kluber’s, rather than the slider I had, which just had a little bit of depth. This year I’m finally figuring it out. Having Kluber on my team, I could talk to him about his grip, what his mentality is, what he’s trying to do at release.

“A big thing for me was, because I wanted to get that sweep and horizontal, I would get really rotational with my body to try to pull it sideways. [Kluber] said that’s the opposite of what you want to do. He said to just let the grip do the work.

“The grip… I put my middle finger right on the seam and really try to crank my middle finger. My pointer finger just rests. So that middle finger is hard pressure, gripping it as hard as I can, and at release I just really pull on that seam.

“When I was in college, I was trying to make it harder and shorter, so I changed to more of a cutter grip where it was just an offset four-seamer. But then it became too small to where there wasn’t much differential [from] my fastball velocity, so I needed to get it back to bigger. When I got it bigger, it had more of a curveball profile and was more up-and-down. I needed to get the sweep, so I changed the grip to feel like I was really on the side of the ball. I called it ‘The last 10%.’ I was really holding on to the side of the ball, and at release was trying to pull that 10%. I was getting sweep to it, but it was like 75 mph, and that’s not a slider.

“Now it’s like the Kluber ball. It has the horizontal movement of a curveball, but the vertical movement of a slider. Kluber doesn’t even know what to call his — he just calls it a breaking ball — and that’s kind of the road I’m going down now. But I do call it a slider.”

———

Lucas Luetge, New York Yankees

“I learned my slider about four years into pro ball. I went back to my junior college coach and told him, ‘Hey, my curveball isn’t really working; I need to have something else that I can throw.’ He originally taught me a cutter. He said, ‘Start throwing this hard, so you get velocity and it differentiates from your curveball. Over time it will start to morph into a slider.’ That’s what happened.

“He wanted to emphasize throwing the ball hard, instead of trying to make it move. He said if I just trust the grip, it will move. Honestly, that’s how the conversation went. I threw a bullpen with it and… like I said, at first it was a cutter — real small — and it just slowly got bigger and bigger. It’s a standard slider grip.

”That was kind of the next step in my career, because before that I was just doing okay. I was going into my Rule 5 year and needed to be put on the 40-man. I think that’s what got me Rule 5’d by the Mariners. They used me as lefty-lefty guy.

“My curveball is around 73-75 [mph] and my slider is 80-82. They’re completely different pitch forms. It used to be… I’m older now, and my slider when I first started throwing it was 84-85. Now it’s gotten a little bigger, with more depth. I think teams are actually kind of looking for that.

“When I talk to guys [about throwing a slider], I tell them to grip it with a stiff wrist — but whatever feels comfortable — and don’t try to make it move, just trust that the grip is going to make it move. The biggest problem when guys try to make a slider move more is that it gets loose and sloppy. That’s when a hitter can see it better. The more you move your wrist, the less tight it will be. When I say tight, what I mean is that the hitter sees fastball all the way and then all of a sudden it breaks off — like out of nowhere. So yeah, stiff wrist, grip it hard, and trust that it will move rather than trying to make it move.”

———

Jordan Romano, Toronto Blue Jays

“I first started learning a slider when I came back from Tommy John surgery. That was in 2016 — I was a starter at the time — and it was in the 83-84 [mph] range. It was more of a slurve.

“After my first [big-league season], in 2019… my slider was still a little slow. It was 85-ish and I wanted something harder, so I worked with one of our coaches, Matt Buschmann. We tried this different grip and I started to throw it harder. The past two years it’s been from 85 to 92.

“We’ve learned that 88-89 is when it breaks the most and has the most success, so I try to throw it in that range. Ideally I’m getting bullet spin — I want it going more straight down than side-to-side — although it doesn’t always happen that way. It’s also not a high-spinning slider; it’s more of a low spin. But again, I want it to go straight down, almost like a curveball.

“The grip… before, I kind of threw it with a lot of finger on the seam. Now, I’ve kind of rotated the thumb and have a little piece of my finger on it. [Buschmann] was like, ‘Instead of having most of your fingers on the seam… you can get more spin, but it’s going to be slower. Try holding it with kind of just finger pads on the seam, so there’s not as much on there.’ So I went from thumb on the seam to thumb on the side, and that helps me throw it harder. With the thumb on the seam, it’s going to be a little slower, a little bigger. That’s not what we wanted. We wanted it to be more of a gyro slider.”