Pitchers who changed their pitch mix mid-season — a new offering, a shelved one, or a big usage shift — and what it's done to their results. Arsenal changes are the most common mechanism behind in-season breakouts.
Arsenal Shifts
Pitchers whose pitch usage in the last 30 days has shifted vs their season baseline, ranked by shift magnitude × that pitch’s whiff% × K-rate uplift.The buy-low play — adopt a high-whiff offering before ownership notices.
New weaponLeaning on a high-whiff/plus-Stuff+ pitch more, and the strikeout rate over this window confirms it.
EmergingAdopting a plus pitch more often — results haven't fully shown up in the K rate yet.
WatchThrowing a below-average-whiff pitch more — a mix change without an obvious edge.
SheddingThe headline change is throwing a pitch notably less.
Recent usage window from statcast_pitches; season baseline from stuff_plus_arsenal. K/9, ERA and IP are computed over the same 30-day window as the usage shift (per-game logs), so an L30 shift is judged against L30 results — not a fixed L14. Sample gate: ≥30 pitches in the recent window AND ≥5 instances of the pitch. Minimum |Δ| 3pp to surface. Composite = |Δpp| × pitch whiff% × (1 + L30 K/9 uplift over season).