The arsenal: velo, spin, movement, whiffs, chases

Statcast measures every pitch: release speed, spin rate (rpm), and movement — how many inches the pitch breaks versus a hypothetical spinless ball. Movement is where the 91-beats-99 answer lives: a fastball with elite backspin 'rises' (falls less than gravity says), and hitters swing under it regardless of velo.

Did it work? Two honest outcomes

Whiff% — of the swings against a pitch, how many missed? The purest 'is this pitch hard to hit'. Chase% — how often do hitters swing at it out of the zone? That's deception. A pitch that gets both is a weapon; a hard fastball with neither is batting practice.

The movement plot on any pitcher's page draws the whole arsenal — each dot one pitch, clustered by type. Wide separation between clusters means the hitter must defend multiple movement profiles off the same release. That geometry, more than raw velocity, is modern pitching.