With San Francisco Giants ace Kevin Gausman generating NL CY Young consideration for much of the 2021 season, the effectiveness of the splitter has become a hot topic of conversation. Let’s take a deep dive to gain a better understanding of the characteristics of this particular pitch. A splitter is an off-speed pitch that should play directly off of a fastball, similar to the use of a changeup. It has reduced spin rate due to a stiffer wrist and wide grip (fingers placed on the outside of the baseball) which induces downward movement with occasional horizontal break.
The Splitter Grip
Without discussing arm path and other mechanical components that contribute to pitch movement, thumb placement and finger pressure are two key elements to achieving a desired movement outcome. Splitters that are gripped with the thumb further on the side of the baseball with higher pressure on the pointer finger (pictured on the left) generally result in more arm-side fade, whereas thumb placement under the ball with balanced pressure between the middle and pointer fingers upon release (pictured on the right) tend to result in more vertical drop.
Splitters vs. Fastballs
Before we dive into any Baseball Savant data, it is important to note that the site includes the effect of gravity in their movement profiles (click here to read more “These pitches move more than any other”). That being said, when analyzing data of the 51 pitchers who threw a splitter and at least 100 total pitches over the course of the 2021 MLB season, the average splitter traveled 85.7 MPH with a spin rate of 1,290 RPMs, 9.5 inches of horizontal break, and 32.6 inches of vertical depth.
In contrast, the average fastball of the group traveled 93.6 MPH with a spin rate of 2,229 RPMs, and possessed 8.8 inches of horizontal break as well as 17 inches of vertical depth. So, in comparison to a fastball, MLB pitchers in 2021 threw their splitter an average of 7.9 MPH slower with 939.3 fewer RPMs of spin, 0.7 more inches of horizontal break, and 15.6 more inches of vertical depth.
Evaluating the Splitter (with a little help from Fangraphs)
Fangraphs’ pitch type linear weights tool enables us to determine the effectiveness of each pitcher’s splitter over the course of a season. These metrics use fluctuations in run expectancy from count to count to quantify the success of each individual pitch within a pitcher’s arsenal. More specifically, wSF represents the total number of runs that a pitcher saves with his splitter over the course of a season, whereas wSF/C represents the total number of runs a pitcher saves on a per 100 pitch basis.
As you can see, Kevin Gausman is near the top of the list in terms of wSF/C at 1.60, and at the very top of the list in Total Runs Above Average for a Splitter at 17.6 (not surprising with his 35.4% usage rate). What specifically makes this pitch so effective?
Kevin Gausman’s Splitter
When comparing the average velocities of Gausman’s 4-Seam Fastball (94.6 MPH) and Splitter (83.6 MPH), the 11 MPH gap presents a healthy differentiation between the two pitches. Because the pitch is designed to look like a fastball out of the hand, the hitter is forced to commit to his swing early, causing him to be out in front as it bottoms out. With this sizable velo gap, along with 755 less RPMs of spin, and 22.8 inches more depth than the fastball, it is almost impossible for a hitter to adjust off-speed while also protecting against the 94-96 MPH heater.
Here is a great summary of his pitches by frequency, velocity and break patterns.
Additionally, when comparing this particular offering to similar pitches within plus or minus 2 MPH and 0.5 feet of extension and release on Baseball Savant’s Pitch Movement Leaderboard, Gausman’s Splitter actually possesses 4% (1.6 inches) more depth and 17% (1.8 inches) more arm-side run.
Along with Gausman’s ability to kill spin, this added movement is also likely a result of a 1:00 hour deviation in tilt between observed movement and spin-based movement (Click here to learn more “Spin Direction – Pitches Leaderboard”). Due to this drastic change in spin axis, the hitter has a much tougher time recognizing the pitch out of the hand. As shown by Gausman’s 45.9% whiff rate, this delay in pitch recognition has the propensity to lead to more swings and misses.
Kevin Gausman, Wicked Splitters. 🤢 pic.twitter.com/ofxCVWBQNt
— Rob Friedman (@PitchingNinja) September 16, 2021
It is important to note that there is no cookie-cutter strategy to throwing an effective splitter. Pitchers should experiment with different grips and finger pressures in order to build a movement profile that works well in their individual pitch arsenal. Again, what makes a good splitter is how it plays off the rest of your pitches, and particularly the fastball. You can have a nasty splitter, but if there is not enough of a differentiation in movement and velocity from your 4-seam fastball, sinker, etc., it will not create the necessary deception to generate high whiff-rates and soft contact.
By Noah Landow (Data Intern at RPP Baseball)
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