What Is a Prop Bet?
It was a Wednesday night in November 2019, and Vanessa, a sharp NFL bettor who had been crushing spreads for three years, decided to try her hand at props for the first time.
She pulled up DraftKings and saw a prop that looked like free money:
Patrick Mahomes Over 1.5 Passing Touchdowns (-150)
Vanessa thought: "Mahomes averages 3 TDs per game. This is a lock."
She bet $300 to win $200. Mahomes threw for 4 touchdowns. Vanessa won.
But here is what Vanessa didn't know:
- At FanDuel, the same prop was -130 (bet $260 to win $200)
- At BetMGM, it was -140 (bet $280 to win $200)
- At Caesars, it was -135 (bet $270 to win $200)
By not line shopping, Vanessa risked $40 more than she needed to. She won the bet, but she lost money relative to what she could have won. Over a season of 100 bets, that is $4,000 in unnecessary risk—not from bad picks, but from bad process.
Key Insight
You can have the best projections in the world, but if you don't understand vig, line shopping, and market structure, you are going to lose.
The Definition
A proposition bet (or "prop bet") is a wager on a specific occurrence, or non-occurrence, within a game that doesn't necessarily relate to the final outcome.
Unlike betting on the spread or total, where you are predicting the outcome of the entire game, props isolate a single element: a player's performance, a team stat, or a specific event.
Quick Examples
| Prop Type | Example |
|---|---|
| NBA Player Performance | Will Jayson Tatum score more than 26.5 points? |
| MLB Pitcher Performance | Will Gerrit Cole strike out more than 7.5 batters? |
| NFL Derivative Prop | Will Travis Kelce score a touchdown? |
| Novelty Prop | Will the coin toss be heads or tails? (Avoid these entirely) |
Why Props Are Different
This isolation is what makes props both more exploitable and more volatile:
More Exploitable
- Fewer variables to analyze
- More information asymmetries
- Books can't specialize in every player
- Late-breaking news creates edges
More Volatile
- One player's performance is inherently less predictable than a team's
- Higher variance in outcomes
- Smaller sample sizes for analysis
Warning
Props have significantly higher variance than traditional bets because they are based on the performance of a single player rather than a team. Even if you are a winning bettor with a 55% win rate, you will face losing streaks.
The Fundamental Truth
The truth is, you can have the best projections in the world, but if you don't understand:
- Vig (the sportsbook's built-in fee)
- Line shopping (finding the best price)
- Market structure (how props are priced)
...you are going to lose.
This chapter will break down the fundamental mechanics of prop betting: what props are, how they are structured, how books make money, and most importantly, how you can tilt the math in your favor before you ever build a model or analyze a matchup.
📝 Exercise
Instructions
Test your understanding of what distinguishes prop bets from traditional betting markets.
Which of the following is the BEST definition of a prop bet?
Why are prop bets considered MORE exploitable than main markets?
What was Vanessa's mistake in the opening story?