Tyler Rogers pitching for the San Francisco Giants, CCed by Liscense 2.0
Baseball research has long sought to quantify and explain what causes a pitch to be successful. This research has led to player development changes over the years such as chasing more carry on a fastball or adding a sweeper to a player’s repertoire. We know that pitch characteristics such as a flat vertical approach angle will lead to more swings and misses as hitters are more prone to swing underneath the ball. Now, Statcast and Baseball Savant have made arm angle data available to the general public, which can be found here. This information provides a more comprehensive approach to understanding why pitches may or may not be effective at the big league level. Here, I’ll be discussing what this information tells us, why it’s important, and who is good at it.
The new arm angle data gives a visualization for where the arm is positioned at release. Guys that are over the top, like Jose Alvarado, will be closer to 60 degrees. As pitchers creep closer to a sidearm slot, the angle gets closer to 0 degrees. For example, Chris Sale is at 11 degrees, and notorious submariner Tyler Rogers releases the ball with his arm at an absurd -64 degrees. It’s easy to estimate the arm angle by simply watching the pitcher throw, but having the data actually available opens up the door for more analysis into what makes a pitch perform better or worse in a game.
When pitch tracking data became available, it opened the floodgates for understanding and quantifying the effectiveness of the pitch. The dead zone became a term for fastballs that were “flat” to the hitter and therefore easy to hit. The dead zone was essentially defined as the pitch having similar or equal amounts of induced vertical and horizontal break. While this certainly provides an explanation, it does lack the nuance of taking the arm angle at release into consideration. A Tyler Rogers fastball will perform differently and look different to the hitter than a Chris Sale fastball with the exact same vertical and horizontal break would. This is because of the position that the arm and hand are in when the ball is released. The pitch does not enter the zone in 2 dimensions as it shows up on a movement plot, but rather in 3 where the release height and angle determine how the pitch enters the zone and appears to the hitter.
Max Bay is a baseball researcher and data scientist who co-created Stuff+ for Fangraphs and previously worked for the Houston Astros. He’s back on the public side now, and he has released some incredible new work in quantifying and visualizing the dead zone. The visualizations show the dead zone as the expected shape of the fastball given the release position and angle. The link to the app can be found here. You can select any pitcher and get a visual on how unexpected each fastball appears to the hitter. Bay offers an explanation and primer on how the calculations are performed on the app as well. Statcast and Baseball Savant offer a visual on each player’s page as well, but I find Bay’s to be more insightful and useful. It’s rather intuitive that pitches that are unfamiliar and perform different than the hitter would be expecting would yield better results, whether it be a swing and miss or a poorly hit ball. Let’s look at some of the pitchers who offer really unique and unexpected fastballs to hitters.
This is the visualization for Jack Flaherty’s four-seam fastball and sinker. As the shade gets darker, it indicates that the pitch is moving in a way that is unexpected given the release angle and arm positioning at release. Here, we see his four-seam fastball features an unexpected amount of ride and gloveside movement or cut. The sinker on the other hand drops and has less vertical break than expected. The combination allows Flaherty to offer two distinct and unexpected fastball shapes to the hitter. He doesn’t throw the sinker more than 2% of the time, but he does rely on his fastball 43% of the time. With the four-seam, he’s generated a 23.8% whiff rate and a .309 wOBA. Fastball usage around the league has trended down significantly over the years, and it’s easy to understand why. The fastball is usually the easiest pitch to hit, unless it is significantly unexpected for the hitter. Flaherty limits damage fairly well with the fastball due to its unexpected nature.
Shota Imanaga is shown here with unexpected ride on his fastball and sink on his sinker. He only threw the sinker 2% of the time this year as well, but relied heavily on his fastball, using it at a 52% rate. The pitch was incredibly effective, and he put up a run value of 7 with the pitch in 2024. Not only does the pitch have more ride and carry than expected, but his release height is fairly low which makes the ball appear very flat to the hitter as it approaches and enters the hitting zone. Because of this, opposing hitters struggle to match plane with their barrel as they swing the bat, which yields weak contact or swings and misses more consistently.
The best closer in baseball, Emmanuel Clase’s four-seam fastball may be in the dead zone, but his cutter offers a completely unexpected look to the hitter. He only threw the four-seam 1% of the time, but he relied almost exclusively on the cutters in many outings, throwing it 78% of the time, and for good reason. The pitch posted a gaudy run value of 23, and opposing hitters put up a wOBA of .194 against the pitch in 2024. Truly a generational pitch, and the visualizations back this up and show how unexpected and unique the pitch is.
Yu Darvish is one of the more fun pitchers in the game, offering up 7 different pitches. Here, we see 3 of them with his four-seam, cutter and sinker. The cutter performs most unexpectedly, and while the four-seam acts closest to its expected movement, his sinker offers a more unique look to the armside for the hitter.
These visualizations offer a perspective that is more all-encompassing and more informative than a movement plot by taking more factors into consideration and comparing the pitch to the expected movement outcome.
Going forward, I would not be surprised to see more teams and players looking to add different fastballs to their arsenals in order to provide different, unexpected looks to hitters. Pitchers that are supinators are generally able to manipulate the outside of the baseball more effectively than pronators, and they are prime candidates to add cutters and sinkers that take advantage of seam-shift effects. I would not be surprised to see more organizations target pitchers with these release preferences, as adding more pitches that move in an unexpected manner amplifies the guessing game that the hitter is already playing in the box and makes it all the more difficult to produce damage, which is ultimately the goal of pitching.
