Tanner Houck Is Embracing the Splitter Revolution

That is the 12 months 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 enhance of 41%. Aficionados of the split-fingered fastball embrace 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 12 months. 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 12 months 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 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 12 months, he posted an ERA above 5 and struggled to get outs as his pitches misplaced their chew later in begins.

Except for stamina, Houck’s supply served as a hurdle to his skills as a starter. Whereas a handful of starters hearth from low arm slots, Houck is likely one of the solely true sidearmers presently in a giant league rotation. He doesn’t have an outlier launch level because of 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 an ideal viewing angle for left-handed hitters, who comprise nearly all 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 the whole season. However by way of his first 10 begins of this 12 months, he’s held them to a line so poor I can’t discover a certified hitter whose numbers I can examine 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 method to pitching appeared like earlier than ramping up the usage of 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 resulting from 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 inclined to generate giant platoon splits, compounding with the benefit lefties acquire 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, desperate to get hammered. Prior to now, Houck primarily used four-seamers and cutters as his arduous choices towards lefty opponents, hoping the rising motion can 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 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 grew to become 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 grime. 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 charge and putaway charge, 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 considered one of only a dozen with a adverse common launch angle. After years of permitting lefties to crush the ball within the air, he’s inducing the next groundball charge towards lefties than righties in 2024. These underlying modifications have manifested in huge time outcomes – lefties have only a .038 ISO towards Houck this season and have but to homer, and Statcast metrics like barrel charge affirm that is no fluke.

The emergence of Houck’s splitter has additionally lower down his stroll charge considerably, as he’s jumped from the forty second to the 88th percentile in avoiding free passes. Beforehand, Houck typically nibbled across the zone towards lefties, afraid of what they might 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 charge by 14 share factors and his general zone charge by almost 5.

The effectiveness of his splitter has additionally made Houck’s sinker a more practical strike stealer as a result of hitters watch it go by anticipating it to drop beneath the zone. Houck presently ranks second to Seth Lugo in referred to as strike charge, getting forward of hitters earlier than disposing of them with the slider and splitter. His improved management of the depend is a giant motive why he ranks fourth in Okay-BB% enhance 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 change into a two-pitch pitcher towards lefties, throwing both a slider or splitter almost three-quarters of the time.

It’s not typically that you just see a pitcher use two completely different non-fastballs as their major choices, however this technique has paid off – not only for Houck but in addition for the Purple 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 virtually solely relied on sliders and splitters towards left-handed hitters would have been unthinkable, however the secondaries-first method is now a technique 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 charge — 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 change into a wonderful starter who persistently works into the seventh inning. However with a surprisingly easy repair, Houck has made it occur.