Win Probability

What is Win Probability?

Win Probability is the pre-game estimated chance that a team will win a specific matchup, derived from the Power Rating difference between the two teams. A team with 65% win probability is expected to win that matchup about two-thirds of the time based on their scoring histories.

How Win Probability is calculated

Win Probability is computed from each team's Power Rating model — their estimated scoring mean and variance:

1. Calculate the expected spread: The difference between the two teams' Power Ratings (mean expected scores)
2. Account for variance: Both teams' scoring volatility is combined to estimate the uncertainty of the outcome
3. Convert to probability: A normal distribution CDF converts the spread and combined variance into a probability between 0% and 100%

A team favored by 10 points with low combined variance might have 75% win probability. The same 10-point spread with high combined variance might only be 60%, because volatile teams are more likely to produce unexpected results.

Related metrics

Upsets and dramatic matchups

Win Probability enables upset tracking across your league's history. The system flags:

• Underdog wins: Victories by the team with lower pre-game probability
• Dramatic wins/losses: Outcomes that shifted Championship Odds by 15 percentage points or more
• Critical matchups: Games where any team's playoff odds shifted by more than 10 percentage points

These flags identify the most consequential and surprising games in your league's history.

See win probability in your league

Import your league for free to see pre-game win probabilities for every matchup in your league's history — and discover which upsets changed the course of your seasons.