Tyler Rodgers plays for the San Francisco Giants CCed by Liscense 2.0
Baseball research has long attempted to quantify and explain what leads to pitching success. This research has led to changes in player development over the years, such as driving the fastball more or adding a sweeper to a player’s repertoire. We know that pitch features like a flat vertical approach angle will result in more swings and misses because hitters are more inclined to spin under the ball. Now, Statcast and Baseball Savant have made the arm angle data that can be found available to the general public 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 discuss what this information tells us, why it’s important, and who’s good at it.
The new arm angle data gives an idea of where the arm is at launch. Guys at the top, like Jose Alvarado, will be closer to 60 degrees. As the pitchers creep into the sidearm opening, the angle approaches 0 degrees. For example, Chris Sale is at 11 degrees, and the infamous submariner Tyler Rogers releases the ball with his hand at a ridiculous -64 degrees. It’s easy to estimate arm angle just by watching a pitcher throw, but actually having the data available allows for more analysis of what makes a pitch perform better or worse during a game.
When pitch tracer data became available, it opened the door to understanding and quantifying field performance. Dead zone became the term for fastballs that were “flat” to the hitter and therefore easy to hit. A dead zone is essentially defined as a plane that has a similar or equal amount of vertical and horizontal spacing generated. While this certainly provides an explanation, it lacks the nuance of considering the wing angle. Tyler Rogers’ fastball will display differently and look different to the hitter than Chris Sale’s fastball with the exact same vertical and horizontal spacing. This is due to the position the arm and hand are in when releasing the ball. The zone does not enter in 2 dimensions as it appears on the motion chart, but rather in 3, where the height and angle of the release 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 now back in the public eye, and he’s released some incredible new work to quantify and visualize the dead zone. The visualizations show the dead zone as the expected shape of a fastball given launch position and angle. A link to the app can be found here here. You can pick any pitcher and get a visual of how unexpected each fastball is to the hitter. Bay offers an explanation and primer on how the calculations are done in the app as well. Statcast and Baseball Savant also offer a visual on each player’s page, but I find Bay’s to be more insightful and helpful. It’s pretty intuitive that pitches that are unfamiliar and different from the hitter than the hitter expected will produce better results, whether it’s a swing and miss or a poorly hit ball. Let’s take a look at some pitchers that offer really unique and unexpected fastballs to hitters.
This is an illustration of Jack Flaherty’s four-seam fastball and mushroom. As the shade becomes darker, it indicates that the pitch is moving unexpectedly, given the angle of release and the position of the hand at the time of release. Here we see that his four-seam fastball takes an unexpected walk and has movement or cut near the glove. On the other hand, the sinker falls and has less vertical crack 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 relies on his fastball 43% of the time. Through four strikeouts, he has a 23.8% slugging rate and a .309 wOBA. The use of the fastball in the league has declined significantly over the years, and it’s easy to see why. The fastball is usually the easiest pitch to hit unless it is significantly unexpected to the hitter. Flaherty does a pretty good job of limiting damage with the fastball because of its unexpected nature.
Shota Imanaga is shown here with an unexpected walk on his fastball and a dive on his sinker. He’s thrown the sinker just 2% again this year, but has relied heavily on his fastball, using it at a 52% rate. The pitch was incredibly effective and he had a 7 rating with the pitch in 2024. batter as he approaches and enters the strike zone. Because of this, opposing hitters swing the bat to try to match the plane with their barrel, which is slack or swing and miss more consistently.
Baseball’s best closer, Emmanuel Claeys’ four-seam fastball may land in the dead zone, but his cutter gives the hitter a completely unexpected look. He only threw the four seam 1% of the time, but in most outings he relied almost exclusively on cutters, throwing it 78% of the time, and for good reason. The pitch posted 23 runs worth, and opposing hitters posted a .194 wOBA against the pitch in 2024. Truly a generational pitch and the visuals back it up and show just how unexpected and unique the pitch is.
Yu Darvish is one of the more entertaining pitchers in the game, offering 7 different pitches. Here we see 3 of them with its square, cutter and sinker. The cutter is the most unexpected, and while the four-seamer is the closest to its expected movement, its sinker gives a more unique look to the hitter’s arm.
These visualizations offer a perspective that is more comprehensive and informative than a motion plot, taking into account more factors and comparing the height to the expected outcome of the motion.
Going forward, I wouldn’t be surprised to see more teams and players looking to add different fastballs to their arsenal to give hitters different, unexpected looks. Pitchers who are supinators are generally able to manipulate the outside of the baseball more effectively than pronators, and are prime candidates for adding cutters and sinkers that take advantage of seam displacement effects. I wouldn’t be surprised to see more organizations target pitchers with preferences this edition, as adding more swinging pitches unexpectedly increases the guessing game that a hitter is already playing in the box and makes it harder to cause damage. which is ultimately the purpose of pitching.
