Definition
Prop bet (proposition bet) wagers on a specific player or event outcome unrelated to the final score. Types: player props (passing yards, receiving touchdowns), game props (first team to score, total sacks), exotic props (coin flip, halftime show length). Books set props using shallower models than spreads, creating larger edges for well-researched bettors. Player props depend heavily on game script, snap share, and usage that books often underprice.
Worked Example
Patrick Mahomes passing yards line: 285.5 (−110 over / −110 under). Your model projects 302 yards based on opponent DVOA, weather, and pace. Implied probability of over at −110 = 52.38%. If your model gives 58% probability of going over, edge = 58% − 52.38% = 5.62% per bet.
Why It Matters
Prop markets are softer than spread markets. Books allocate less pricing sophistication to props, so sharp player-usage modeling finds more frequent edges here than in mainline spreads.