Tanner Houck Is Embracing the Splitter Revolution

That is the yr of the splitter. In 2024, 3.1% of all large league pitches thrown have been splitters in comparison with 2.2% in 2023, a year-over-year improve of 41%. Aficionados of the split-fingered fastball embody former NPB stars like Yoshinobu Yamamoto and Shota Imanaga, longtime MLB customers like Joe Ryan and Fernando Cruz, and an assorted assortment of hurlers who’ve added a brand new splitter or featured one way more prominently of their arsenal this yr. And few starters have scaled up their splitter utilization greater than the person atop the pitcher WAR leaderboard: Tanner Houck.

Houck has thrown a splitter his whole time within the majors, however he’s taken it to a brand new stage this yr by doubling its utilization. Amongst certified starters, Houck throws the sixth-highest share of splitters, whereas his splitter’s 110 Pitching+ ranks fifth, forward of Ryan and Imanaga. The rise of Houck’s splitter, mixed with the arsenal tweaks he’s made to throw it extra, have remodeled him from a mixed-role swingman to slam-dunk frontline starter.

Houck has spent most of his large league profession straddling the road between starter and reliever. He pitched primarily as a starter throughout his 2021 rookie season, however by no means accomplished the sixth inning in any of his begins. His sophomore marketing campaign noticed him make multi-inning appearances out of the bullpen. Again within the rotation final yr, he posted an ERA above 5 and struggled to get outs as his pitches misplaced their chunk later in begins.

Other than stamina, Houck’s supply served as a hurdle to his talents as a starter. Whereas a handful of starters hearth from low arm slots, Houck is among the solely true sidearmers at present in an enormous league rotation. He doesn’t have an outlier launch level due to his tall stature and mechanics that carry him towards the primary base aspect, however his arm angle is definitely the bottom amongst starters. Houck’s supply supplies a terrific viewing angle for left-handed hitters, who comprise the vast majority of his competitors as opponents stack platoon bats towards him.

In 2023, lefties slashed .271/.356/.502 towards Houck, roughly the equal of getting to face Rafael Devers for your complete season. However via his first 10 begins of this yr, he’s held them to a line so poor I can’t discover a certified hitter whose numbers I can evaluate with it. Neutralizing the platoon benefit is a big deal for a pitcher along with his arm angle, and far of this spectacular feat has to do along with his splitter.

Let’s check out what Houck’s strategy to pitching regarded like earlier than ramping up using his splitter. Like most low-slot pitchers, his two major choices are a sinker and slider, profiting from the east-west motion his arm motion produces. Each these pitches are chart-topping by way of motion, dropping greater than common because of their lack of backspin, and his slider breaks to the left much more than most sweepers (although Statcast doesn’t classify it as one).

Whereas these two pitches made right-handed hitters completely futile towards Houck, sinkers and sweeping sliders are likely to generate massive platoon splits, compounding with the benefit lefties achieve from seeing the ball clearly out of his hand. Houck’s slider drops a lot that lefties can’t do a lot with it, however his sinker strikes straight into the trail of their barrels, desperate to get hammered. Up to now, Houck primarily used four-seamers and cutters as his onerous choices towards lefty opponents, hoping the rising motion could be sufficient to overlook bats. However these pitches nonetheless had an excessive amount of arm-side motion and didn’t generate upward Magnus pressure, as a substitute staying on aircraft with lefty swings.

Houck’s strategy to lefties wasn’t working, and he wanted a change. In got here the splitter. What was as soon as a distant fourth providing grew to become his offspeed weapon. He tinkered with its form, including practically 4 inches of drop to make it extra distinct from his sinker. He tightened up its command, ending down within the zone extra constantly and spiking fewer within the filth. The top results of these changes is a deadly pitch that has been a key contributor to Houck’s success.

Houck’s splitter leads his arsenal in each swinging strike fee and putaway fee, indicating it’s already his go-to weapon in two-strike counts. And whereas it’s been profitable at lacking bats, the outcomes it generates when batters put it in play could also be much more spectacular. His cut up has the lowest launch angle allowed of any particular person pitch from a starter; it’s one in every of only a dozen with a destructive common launch angle. After years of permitting lefties to crush the ball within the air, he’s inducing the next groundball fee towards lefties than righties in 2024. These underlying adjustments have manifested in large time outcomes – lefties have only a .038 ISO towards Houck this season and have but to homer, and Statcast metrics like barrel fee affirm that is no fluke.

The emergence of Houck’s splitter has additionally minimize down his stroll fee considerably, as he’s jumped from the forty second to the 88th percentile in avoiding free passes. Beforehand, Houck usually nibbled across the zone towards lefties, afraid of what they may do to his fastball and cutter. Now armed with a pitch that limits harm, he’s fearlessly attacking the strike zone, enhancing his splitter zone fee by 14 share factors and his general zone fee by practically 5.

The effectiveness of his splitter has additionally made Houck’s sinker a simpler strike stealer as a result of hitters watch it go by anticipating it to drop beneath the zone. Houck at present ranks second to Seth Lugo in known as strike fee, getting forward of hitters earlier than disposing of them with the slider and splitter. His improved management of the rely is an enormous cause why he ranks fourth in Ok-BB% improve relative to 2023.

What impresses me most about Houck’s splitter is the sheer frequency with which he deploys it towards lefties, particularly on the expense of his fastballs. He’s throwing considerably fewer cutters and has shelved the four-seamer solely. After unsuccessfully throwing the kitchen sink towards opposite-handed opponents, he’s basically turn out to be a two-pitch pitcher towards lefties, throwing both a slider or splitter practically three-quarters of the time.

It’s not usually that you just see a pitcher use two totally different non-fastballs as their major choices, however this technique has paid off – not only for Houck but additionally for the Crimson Sox as an entire. Final month, Chris Gilligan wrote about Boston’s workers main the leaguewide shift away from the fastball, stating Houck’s four-seamer had a horizontal motion profile ripe for hitters to feast on. Only a couple a long time in the past, a beginning pitcher who nearly completely relied on sliders and splitters towards left-handed hitters would have been unthinkable, however the secondaries-first strategy is now a method that whole groups are embracing with large outcomes.

Houck’s run because the top-performing pitcher within the majors most likely received’t final — he has an unsustainably low 2.6% HR/FB fee — however the excellence of his splitter has definitely put a large up arrow on his future projection. Only a couple years in the past, it will’ve been troublesome to check that the sidewinding swingman who couldn’t deal with lefties would turn out to be a wonderful starter who constantly works into the seventh inning. However with a surprisingly easy repair, Houck has made it occur.