William Kempner

What they throw, how hard, and what misses bats — from pitch tracking, regular season only.

How the mix shifts against lefty and righty bats. Medians are among right-handed pitchers who throw that pitch at least 3% of the time — 355 of them. Overall results by batter side are under Platoon splits.

Each dot is a pitch's current shape — horizontal break (arm side vs. glove side) by induced vertical break (rise vs. drop). Both axes are in inches of break. The trail runs from this season's earliest tracked outings — the faint, thin end — up to today's solid dot; a trail with only a few segments just means fewer tracked outings. The soft halo around each dot is how far that dot could sit off on its own, just from ordinary outing-to-outing wobble. Don't read a long trail as proof on its own that a pitch changed. Every pitch in baseball loses a little break through midsummer and gets it back by September — the same shift two full seasons back agree on — and the trail shows that league-wide seasonal swing alongside whatever this pitcher did himself. The sentence at the top of this card has the league's share taken out, so it can read “has not moved” above a trail that looks long. That is the two marks measuring different things, not a mistake. A pitch counts as changed only once it sits at least two inches from its own early-season shape — a verdict about this pitcher against himself, never a comparison with anyone else. League median: the small hollow ring marks it, on the same two measurements. Where it sits far from a pitch's dot, a line joins the two — and on a wider screen the ring carries that pitch's code as well — so a distant ring is never orphaned; where it sits close, neither is drawn, because the pairing is already obvious. League median is missing entirely for a pitch marked *: too few pitchers throw it for one to be worth setting, so it is plotted without a reference ring. For the exact dates a pitch changed, see the by-appearance chart below.