HR Prop — Fair-Value Dashboard

pick a hitter · live data fills the model · you compare to the market

What this is

A fair-value estimate of the chance a hitter homers in a given game. Pick a date and a hitter — the model finds their game, pulls live data, and prices the prop as American odds. You type in the book's price to see if there's an edge. Nothing is bet automatically.

It estimates expected home runs λ from the inputs below, then P(≥1 HR) = 1 − e−λ. Inputs folded into every price:

Hitter HR/PA — career + season + recent blend Expected PA by lineup slot Opposing starter & bullpen HR allowed Handedness platoon (L/R) Ballpark HR factor Weather — temp & wind to center Schedule / fatigue & health
Pick a date, then start typing a hitter — the model finds their game automatically.
—
+1952.95
Model Prob
33.9%
Expected HR (λ)
0.414
Per-PA HR
9.1%
COMPARE TO MARKET
Type the book's price. Nothing is fetched — you enter it.
Enter market odds to compare
Market Implied
—
Prob Edge
—
EV / $100
—

Hitter Baselinep₀ 7.28%

Blend of career, season and recent HR/PA. Recent is noisy — keep its weight low.

Playing Time4.55 PA

Lineup slot sets expected PA (defaults are manual — confirmed lineups post ~2–4h pregame).

vs Starter 2.59 PA · vs Pen 1.96 PA

Pitching Matchup×1.02

Odds-ratio: batter rate scaled by each arm's HR/PA allowed vs league. Platoon auto-fills from splits.

Ballpark×1.18

Handedness HR park factor (1.00 neutral). Auto-set from the home venue & hitter's side.

Weather & Air×1.14

~1% HR per °F off 70°F; wind out/in to center adds or removes carry. Closed roof neutralizes both.

Temp ×1.14 · Wind ×1.00

Schedule & Health×0.99

Manual nudges for travel fatigue, back-to-backs, and injuries. Rested & healthy = 1.00.

Price Attribution

Baseline per-PA rate bent by each factor, then compounded across expected trips into λ. Bars center at 1.00.

FactorEffect (centered at 1.00)MultRunning p
λ → P(≥1 HR) — 0.414 33.9%