The share of a hitter's batted balls that are 'barrels' — the exit-velocity and launch-angle combinations that historically produce elite results.
A barrel is a batted ball whose combination of exit velocity and launch angle has historically led to very high batting average and slugging — the contact every hitter is trying to make. The barrel zone starts around 98 mph of exit velocity and widens in launch-angle range as the ball is hit harder.
Barrel rate is usually expressed as barrels per batted-ball event. It is one of the most stable and predictive single indicators of power because it captures both how hard and how ideally a hitter squares the ball up.
Barrel rate is a core power input. A high-barrel hitter facing a pitcher who allows barrels is one of the cleaner setups the home-run model looks for.
A barrel is a batted ball with the exit-velocity and launch-angle combination that has historically produced at least a .500 batting average and 1.500 slugging. It generally requires about 98 mph of exit velocity, with a launch-angle window that widens as the ball is hit harder.
Barrel rate is a process metric and tends to stabilize faster than home-run totals, which are a noisy, low-frequency outcome. It is best used alongside the home-run rate it helps explain, not instead of it.