Predicting goalscorers: breaking down shot volume and shot quality

The legacy anytime-scorer rate input was a single per-90 aggregate: npxG_per_90 = total_npxG / nineties, drawn from each player's most recent ≥500-minute club season. That collapses two distinct signals — how often the player shoots (volume) and how dangerous each shot is (quality) — into one number, which mis-rates two specific edge cases:

1. Low-volume, high-per-shot outliers. A defender who took 3 shots in a season and happened to convert at 0.40 npxG/shot extrapolates to a wil…