Tanner Houck on Learning and Developing His Splitter

Tanner Houck’s signature pitch is a sweeping slider. The 25-year-old Boston Red Sox right-hander has gone to it 35.5% of the time this season, and with good results. There is little question that the offering is the most lethal weapon in his arsenal. That said, it’s arguably not his most important pitch going forward — particularly if his future is in the starting rotation, and not out of the bullpen.

Bedeviled by an inability to master a conventional changeup, Houck began learning a split-finger fastball last year. The pitch remains something of a work-in-progress, yet he’s begun throwing it more frequently. Houck’s splitter usage is up to 7.5% on the season, a percentage that promises to rise if he can fine-tune it further. Four years after he was drafted 24th overall out of the University of Missouri, Houck is hoping that his newest pitch will take him to the next level.


Tanner Houck: “I had trouble throwing a changeup. I would constantly baby it — I would get on the side of it and just push it — so it was really inconsistent. They came to me and said, ‘Hey, we want you to throw a splitter.’ This was in spring training 2020, four days before we got canceled. It was a heck of a time to start learning a new pitch.

“They wanted me to keep working on the change, but also attempt to throw the splitter, and I was like, ‘OK, fine; I’ll give it a shot.’ I threw a bullpen the next day, and for every five, maybe one of them wasn’t too bad. At that time it was still 90-93 [mph]; it was essentially just a little bit worse of a two-seam. But I didn’t think anything of it. I was like, ‘This is literally day one of throwing this pitch, so it’s not a big deal.’ Then COVID happens, so I go home.

“I was throwing to a high school buddy and told him that I was working on a new pitch; I was going to have a splitter. I played with it for three weeks — we were throwing in a park — and at that point it was, ‘OK, I guess it’s not a terrible pitch.’ I didn’t really know what to do, because I didn’t have anyone to give me tips, or tricks, or anything like that.

“Fast forward to the alt site: I’m still throwing the splitter and the changeup. I’m working with [Triple-A pitching coach] Paul Abbott, trying to get consistency with the action. I was able to throw the splitter in the strike zone more often, so it was kind of, ‘Let’s stop with the changeup and fully commit to the splitter for at least a week.’ I was fine with that. And it just kind of stuck. I never looked back once I committed to the split.

“I realized that if got my hand on top of it more, and worked down on the ball, I wouldn’t find myself babying it. I wouldn’t be manipulating it, trying to get side-to-side action, it was just, ‘Hey, I’m going to create this pitch that’s straight down.’ It felt right. It felt like I was throwing it hard. I hear people saying that a splitter kind of just slips out, but I don’t necessarily feel like mine slips out. I just get on top of it more and kind of just let it go through the fingers.

“I knew at the alt site that it was one of those pitches that would be good once I got it to be more consistent. But at that time, it was still 87-91. I’d killed a little bit of velo on it, but not as much I wanted. Since then, I’ve been able to kill even more velo on it, which I do by landing with a softer front side. Normally, when you throw a fastball, or whatever pitch, your front leg ends up locking out at some point. On the splitter, I’ve tried to deaden the leg; I kind of let the front leg collapse. That way, everything else can stay full speed, but because there’s no… what I compare it to is pulling the [emergency] brake in a car at 50 mph. All of your momentum is still going forward, even though you pulled the E-brake. By doing that, all of a sudden [the velocity] is 83-87.

Tanner Houck’s splitter grip.

“I don’t split my fingers as much as I did at the beginning. Now, I’m just on the outside of the two seams. There’s nothing too particular about it. I don’t think about finger pressure on it too much. I just try to have balanced finger pressure, stay on top of it, and rip it straight down.

“It helps to have guys on the team that throw a splitter. Especially last year, I talked to [Nate] Eovaldi about it a lot. I leaned on him, asking questions to see what his mindset was, and what his grip was. I actually tried his grip — pretty much all of last year — but this year I went back to not being on a seam. I found that when I was gripping a seam, I was getting more spin, and more side-to-side versus getting straight down. So now I don’t grip any seams; I’m just on the leather. Like I said, I just kind of let it go where I feel it… not ‘slip out,’ but kind of just go through the fingertips. If it feels like it’s slipping out, then I’m not in control. But if I’m on top of it and just letting it go, that’s when I’m getting the good action and the good velo separation.

[Hirokazu] Sawamura’s splitter is gross at 90 mph, but I wanted to kill some velocity on mine. I think of it as having two different things with the splitter — movement and velo separation — instead of having just movement or separation. If it’s 88-91 and I’m throwing it after a 95-mph four-seam, there isn’t a ton of difference. MLB hitters are good enough to where that’s not usually enough separation to create much swing-and-miss. But if I’m getting 10 mph of separation, then they have to cover two different things, versus just one.

“It’s a pitch that I feel confident in, and I’ve grown very much with it, so I’m excited to see where it takes me in the future. I’ve had success with it as of late, throwing it off my slider, my two-seam, and my four-seam. I’m continuing to develop it, so I imagine that the usage will go up over time.”


The 2021 installments of the series can be found here.

The 2019 installments of the series can be found here.

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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1 year ago

My favorite rookie pitcher in a while, he generates great whiff (75th percentile). That splitter of his, batters have gone 1-15 against it this year. And he generates 14.8 inches of movement on it. Ranked 4th out of all starters who throw it. Him, Rogers and McClanahan are great to watch.