Which pitchers are the best at weaponizing surprise? SDV ranks them by how effectively they convert mathematically improbable pitches into positive outcomes.
What is Sequence Deception Value?
A surprise pitch is one thrown well below the pitcher's own baseline frequency for
that pitch type in a given count — a pitch the hitter statistically had little reason to expect.
SDV measures what a pitcher does with that element of surprise: does the unexpected pitch
actually fool hitters, or does it get punished anyway?
For each surprise pitch, an outcome weight is assigned (swinging strike = 1.0, called strike = 0.85,
in-play out = 0.7, foul = 0.55, called ball = 0.25, single = 0.1, HR = −0.3, etc.).
SDV Raw is the mean outcome weight across all surprise pitches. SDV (the ranking column) applies
Bayesian shrinkage toward the league mean to stabilize small samples (K = 10).
Minimum 10 surprise pitches to receive an official rank.