MLB Win Margins: One-Run Games and Comfortable Wins

Winning and winning comfortably are different questions. From 2019 to 2026 between 26.6% and 29.4% of regular-season games were decided by exactly one run each season — 27.7% in 2026.

How the model estimates margins

Instead of working from the win probability alone, the model combines each team's full projected run distribution and adds up every final score where the margin is two or more. That keeps margins consistent with the projected run environment: a 55% favourite in a high-scoring park has a better chance of winning big than the same favourite in a low-scoring one, because big innings are more common there.

Does it work?

Across 12,276 backtest games the model said the side it favoured would win by two or more 41.1% of the time on average; it actually happened 41.8% of the time. The Win Margins page lists today's games by that probability, alongside the chance of a one-run game.