Swing%
Share of pitches the hitter swung at.
What Swing% means
Aggressiveness measure. League average ~47%; sustained outliers indicate either a hyper-aggressive (Swaggerty) or ultra-passive (Soto) approach.
What counts as a good Swing%
Lower is better — roughly 52 is poor, 47 average, 44 good, and 41 or better elite.
Also written
swing_rate · swing_per_pitch