Tanner Houck Is Embracing the Splitter Revolution

That is the yr of the splitter. In 2024, 3.1% of all huge 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 far 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 degree this yr by doubling its utilization. Amongst certified starters, Houck throws the sixth-highest proportion 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 reworked him from a mixed-role swingman to slam-dunk frontline starter.

Houck has spent most of his huge 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 chew 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 the moment 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 facet, however his arm angle is definitely the bottom amongst starters. Houck’s supply gives a fantastic viewing angle for left-handed hitters, who comprise the vast majority of his competitors as opponents stack platoon bats in opposition to him.

In 2023, lefties slashed .271/.356/.502 in opposition to Houck, roughly the equal of getting to face Rafael Devers for your complete season. However by 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 large 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 method to pitching regarded like earlier than ramping up the usage of his splitter. Like most low-slot pitchers, his two main choices are a sinker and slider, making the most of the east-west motion his arm motion produces. Each these pitches are chart-topping when it comes to motion, dropping greater than common as a result 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 in opposition to Houck, sinkers and sweeping sliders are inclined 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 instantly into the trail of their barrels, wanting to get hammered. Prior to now, Houck primarily used four-seamers and cutters as his exhausting choices in opposition to 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 an alternative staying on airplane with lefty swings.

Houck’s method to lefties wasn’t working, and he wanted a change. In got here the splitter. What was as soon as a distant fourth providing turned his offspeed weapon. He tinkered with its form, including almost 4 inches of drop to make it extra distinct from his sinker. He tightened up its command, ending down within the zone extra persistently 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 price and putaway price, 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 break up has the bottom launch angle allowed of any particular person pitch from a starter; it’s one in all only a dozen with a unfavourable common launch angle. After years of permitting lefties to crush the ball within the air, he’s inducing a better groundball price in opposition to lefties than righties in 2024. These underlying modifications have manifested in huge time outcomes – lefties have only a .038 ISO in opposition to Houck this season and have but to homer, and Statcast metrics like barrel price verify that is no fluke.

The emergence of Houck’s splitter has additionally reduce down his stroll price considerably, as he’s jumped from the forty second to the 88th percentile in avoiding free passes. Beforehand, Houck usually nibbled across the zone in opposition to 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 price by 14 proportion factors and his total zone price by almost 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 the moment ranks second to Seth Lugo in known as strike price, 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 in opposition to lefties, particularly on the expense of his fastballs. He’s throwing considerably fewer cutters and has shelved the four-seamer totally. After unsuccessfully throwing the kitchen sink in opposition to opposite-handed opponents, he’s basically change into a two-pitch pitcher in opposition to lefties, throwing both a slider or splitter almost three-quarters of the time.

It’s not usually that you simply see a pitcher use two completely different non-fastballs as their main 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 employees main the leaguewide shift away from the fastball, mentioning Houck’s four-seamer had a horizontal motion profile ripe for hitters to feast on. Only a couple many years in the past, a beginning pitcher who nearly solely relied on sliders and splitters in opposition to left-handed hitters would have been unthinkable, however the secondaries-first method is now a technique that whole groups are embracing with great outcomes.

Houck’s run because the top-performing pitcher within the majors in all probability received’t final — he has an unsustainably low 2.6% HR/FB price — however the excellence of his splitter has definitely put an enormous up arrow on his future projection. Only a couple years in the past, it could’ve been tough to ascertain that the sidewinding swingman who couldn’t deal with lefties would change into a superb starter who persistently works into the seventh inning. However with a surprisingly easy repair, Houck has made it occur.