Overview
Exit velocity measures the speed of the ball at the moment it leaves the bat, captured by tracking systems such as Statcast in MLB and TrackMan in NPB. Every batted ball's speed is recorded in real time. Exit velocity emerged as a transformative batting metric from the late 2010s onward. Unlike traditional outcome-based statistics like batting average or home run totals, exit velocity directly measures the quality of contact. A hitter who consistently produces high exit velocities is considered likely to improve results over time, even if current batting averages are modest. Statistically, batted balls exceeding 158 km/h (98.0 mph) are classified as 'hard hit' and carry a dramatically higher probability of becoming hits. The 'barrel zone' concept - combining exit velocity with launch angle to define the conditions most likely to produce extra-base hits - has become a widely used framework for swing adjustments and training programs. NPB's adoption of tracking data is accelerating, and exit velocity is becoming an indispensable metric in player evaluation and scouting.