Steven Bisig-USA TODAY Sports
In my research on JP Sears’ fastball command for my blog Pitch Plots, I discovered a crucial question: Why does a pitch end up where it does? I found that release trajectory is the key variable in determining the location of a pitch. By analyzing release angles along with release height and width, we can predict with high accuracy where a pitch will end up based on its type.
Existing command models like Location+ and PitchingBot Command provide insights into a pitcher’s ability to avoid walks, but they require a large sample size to be reliable and are not consistent from year to year. This led me to develop a new metric called the Kirby Index, which focuses on the command of the four-seam fastball. Despite its limitations, the Kirby Index shows promise in measuring pitch command.
Release angles, both vertical and horizontal, are not widely available statistics, but they play a significant role in understanding pitcher intent and command. By incorporating release trajectories, we can gain a deeper understanding of how pitchers control the location of their pitches.
Using advanced machine learning techniques and a dataset of nearly 230,000 four-seam fastballs thrown during the 2023 season, I found that release trajectories are highly predictive of pitch locations. By focusing solely on release angles, we were able to explain the majority of the variation in fastball locations, showing the power of this information in quantifying a pitcher’s command.
Overall, understanding release trajectories and their impact on pitch locations opens up new possibilities for assessing and improving pitcher command, a traditionally elusive aspect of pitching performance.
