An East-to-West Slider Is Tanner Houck’s Bread and Butter

There were a few good reasons for me to catch up with Tanner Houck this past week. One is that he has arguably been the best starting pitcher in baseball over the first half of the season. Along with a 2.18 ERA and a 2.20 FIP, the 27-year-old Boston Red Sox right-hander boasts the highest WAR (3.6) among big league hurlers. Another is that I’ve been due to ask him about the pitch he relies on most. Per Statcast, Houck has thrown 41.8% sliders, 30.8% sinkers, 24.8% splitters, and 2.6% cutters.

Back in 2019, when he was pitching in Double-A, Houck was featured here at FanGraphs in an interview that focused on his sinker. Two years later, a second interview explored a developing splitter that, as my colleague Kyle Kishimoto detailed just over a month ago, has become an especially effective weapon. Which brings us to the here and now. Interested in both how Houck’s slider has evolved and how it plays within his three-pitch arsenal, I approached him to get some answers.

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David Laurila: How does the slider you’re currently throwing differ from the one you had last year?

Tanner Houck: “It’s a different grip, technically. Last year, I was running up the horseshoe a little too much and not getting as much side-to-side action. This year there is a focus of creating more east-to-west, side-to-side movement with the pitch, as well as on prioritizing throwing it more in bigger situations. It’s my best pitch by far, so I’m leveraging it whenever I can in those big moments.”

Laurila: Has the word ‘sweeper’ worked its way into the conversation?

Houck: “I guess you can categorize it as a sweeper, but I still look at everything as sliders. I guess that’s just the older school part of me; I don’t really know the difference on how you classify sweeper versus slider, or anything like that. It’s whatever you want to call it.

“The first conversation I had with [new Red Sox pitching coach] Andrew Bailey was to get more side-to-side action on the slider. I’m an east-west guy anyway. I’m very rotational, which is kind of my bread and butter. That’s why I throw a sinker. I can’t generate the verticality with a four-seam the same as I can create the negative depth with the sinker.”

Laurila: How much has the movement of your slider changed? Along with more sweep, I assume the vertical has changed as well.

Houck: “I definitely gained a lot of horizontal. The depth… if anything, I would say that it sometimes gets a little bit more vertical in the sense that it sits [from] +2 to -4. That’s where my range is. With sweepers, most people now are trying to get it in the positive range. I don’t mind it being a little bit more depth-y, but not getting past the -5 mark.”

Laurila: The splitter has obviously been a big pitch for you this year. How do you play your splitter off your slider?

Houck: “I think you just kind of treat it like the two-seam. You can kind of tunnel all three of my pitches off of each other really nicely. I think of throwing everything starting arm-side third and playing all three pitches off that line. I’m trusting that the sweeper is going to get all the way across the zone, the splitter is going to be down, and then the two-seam is going to be down with more arm-side run.

“With that combination, all three coming out of the same window, and with the velo difference — the fastball will be anywhere from 91-94, the splitter will be 86 to 90, and then the slider is coming in at 81 to 85 — that’s a range of 10 or so miles an hour with three different movement profiles coming out of the same window.”

Laurila: Looking at your Baseball Savant page recently, I saw that Logan Webb is listed as being similar to you in velocity and movement. Have you seen that?

Houck: “No, but I will say that with [Bailey] coming over from San Francisco, it was kind of an easy adjustment with the splitter grip. This year, I’ve kind of gravitated to more of what [Webb] throws. He calls it a changeup, I call it a splitter, but it’s relatively the same grip, generating more seam-shifted downward action. Bales coming over from San Francisco was a great, because he worked with a guy who is kind of like me. I mean, to have the success Logan Webb has had, that’s something you hope to replicate.”

Laurila: Did Bailey mention Webb when the two of you started working together?

Houck: “He did. In our some of our earlier conversations, he used that comparison in the sense of us both being very east-to-west guys, big sinker, slider, and then a complementary changeup/splitter. Three pitches, and for a while there I want to say that Webb was also throwing a four-seam, but then scrapped it during [Bailey’s] tenure there. Working with him this year has been great. I feel like I’ve learned a lot. I feel like I’ve gotten better. I feel like I’ve matured as a pitcher a lot.”

Laurila: And you’re definitely a mixture of old school and new school in your approach to pitching. That’s something I’ve learned from the handful of conversations we’ve had over the years.

Houck: “Yeah. I definitely understand analytics, because I know that it is a major part of our game. I feel obligated to at least understand all of the lingo, and all of the conversations we have, because it is part of our job. At the same time, I grew up watching a lot of old school baseball. I loved watching before all the analytics. I loved watching the [Adam] Wainwright’s and Chris Carpenters. A.J. Burnett was always a favorite. So, I grew up watching old school guys, but it’s fun. [Analytics] are a tool that can help you only get better in my opinion.”

Laurila: Any final thoughts on pitching, or on the season you’re having?

Houck: “I think the biggest thing for me this year is that I’ve just stuck to my strengths. I don’t necessarily command the glove-side two-seam as well, so that’s a pitch I haven’t really thrown a ton this year. I have a handful of times, and I’ve gotten swings-and-misses and some weak contact, but it’s a pitch I’m still trying to command at a higher clip. That would be beneficial for me. That goes back to the tunneling aspect, trusting your best stuff off of one lane and commanding the zone.”

Laurila: What about your splitter to the glove side? Can you command that reasonably well?

Houck: “I actually do it on accident more than anything. But I generate a lot of swings and misses off of it. Typically, whenever I do misfire it more glove-side, I believe that I catch a little bit better seam. Typically, I feel like those are my best ones. That’s something I’m trying to command a little bit better, too. But again, I’m mostly sticking to my strengths.”