What is pitch-visualizer?

Pitch Visualizer is a Python app built with Streamlit that lets you explore any MLB pitcher's arsenal using Statcast data, the tracking system baseball uses to measure things like pitch speed, spin, and movement. You search for a pitcher by name, choose one or more seasons going back to 2015 when Statcast data begins, and the app generates charts showing how their pitches move, how fast they are thrown, and how often each pitch type is used. The movement chart accounts for whether the pitcher throws left or right handed, adjusting the horizontal break direction so comparisons make sense regardless of handedness. Alongside the charts, the app shows a summary table with average velocity, spin rate, and movement for each pitch type, and that table can be exported as a CSV file for further analysis elsewhere. Data comes from the pybaseball library, which pulls MLB Statcast data, and the visualizations are built with pandas and matplotlib underneath the Streamlit interface. Setup is a simple pip install of the requirements followed by running the app with Streamlit. The README includes a sample walkthrough using pitcher Nolan McLean's 2025 season, showing how his pitch movement, usage, and velocity charts reveal that several of his pitches share similar speed and movement profiles, making them harder for batters to distinguish out of his hand. Planned future additions include a pitcher versus pitcher comparison view, filters based on count, batter handedness, or game situation, and overlays showing pitch outcomes like whiffs or hard contact. No license is stated in the README.