This study introduces an innovative approach to quantify pitcher fatigue, leveraging the rich data provided by the Statcast system. By focusing on detailed pitch-by-pitch data, we aim to uncover how fatigue affects various pitching metrics, potentially impacting a pitcher’s performance within a game. To complement our analytical framework, we also created a Shiny application, enabling a dynamic exploration of pitcher performance data. This tool allows for interactive analysis, offering users the ability to examine and identify pitchers who may benefit from role adjustments based on their fatigue profiles and performance metrics. Integrating this application into our study enriches the decision-making process, providing a practical platform for applying our findings to real-world baseball strategy and pitcher management.