Friday, Jul 24, 2026 The claims desk. Receipts included. POWERED BY LENZ
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SCIENCE

The Claim

Win probability models used in sports analytics (for example, ESPN's NBA win probability model) are generally well-calibrated, and their probabilities align reasonably well with observed outcomes, at least compared with typical human intuition.

The Short Version

The available evidence indicates these win-probability models are broadly calibrated over many games and usually align reasonably well with actual outcomes. They are not perfect: some studies find underdog bias and phase-specific quirks, and they are not clearly superior to simple baseline models. The comparison to human intuition is supported more indirectly than directly, but the overall claim is largely accurate.

Caveats

  • Calibration is a long-run, aggregate property; a probability that looks absurd in one game does not by itself show the model is broken.
  • Evidence for being better than typical human intuition is mostly indirect, based on predictive performance rather than direct comparisons of human probability calibration.
  • These models can have systematic biases, including underestimating underdogs or reacting imperfectly at certain game stages.

The Receipts

  1. Evaluating real-time probabilistic forecasts with application to the NBA

    arXiv

  2. Predicting the winning team in basketball: A novel approach

    PLOS ONE / PubMed Central

  3. Is FPI a Good Bet?

    East Carolina University

  4. A Referee Impact Metric Analysis Using ESPN Win-Probability Data

    arXiv

  5. The Cavaliers Are Overwhelming NBA Finals Favorites

    FiveThirtyEight

  6. A Paradox of Blown Leads: Rethinking Win Probability in Football

    Wharton School, University of Pennsylvania

  7. All win probability models are wrong — Some are useful

    Stats by Lopez

  8. Judging Win Probability Models

    inpredictable

  9. mrkaye97/espn-cfb-win-prob

    GitHub

  10. How Accurate Are ESPN's Win Probabilities?

    YouTube

+ 1 more sources — see the full list on Lenz

Filed Under

ESPNNational Basketball Association