The InningEdge Engine

Every pitch simulated. Every factor shown. The predictions on this site come straight from the engine. You can build on the same output.

What it does

For every MLB game, the engine simulates the game at-bat by at-bat, thousands of times. Early runs go through the day; the final pre-game run is 10,000 simulations about 45 minutes before first pitch, using the posted lineups when they're out.

Each at-bat is resolved from the actual matchup: the batter against the pitcher on the mound, with platoon splits. Around it, the engine accounts for:

• Starting pitchers: season line, recent form, opener detection, returns from the injured list
• Posted lineups and batting order
• Bullpen workload over the last three days, and closer availability
• Park factors, batter-vs-pitcher history, standings and streaks

What you get for each game

• Win probability for both teams
• Score distribution, expected runs and the most likely score
• The factors that moved the prediction, and by how much
• Data-quality flags: lineups and starters confirmed, early or final simulation

How it has actually performed, including where it is overconfident, is on the Track record page.

Example response

{
  "game_id": 778899,
  "date": "2026-07-04",
  "away_team": "SEA",
  "home_team": "NYM",
  "first_pitch": "2026-07-04T16:10:00-07:00",
  "win_probability": {
    "home": 0.574,
    "away": 0.426
  },
  "predicted_winner": "NYM",
  "expected_runs": {
    "home": 4.6,
    "away": 3.9
  },
  "most_likely_score": {
    "home": 4,
    "away": 3
  },
  "factors": [
    {
      "factor": "pitcher_quality_spread",
      "effect": 0.031
    },
    {
      "factor": "home_field",
      "effect": 0.012
    },
    {
      "factor": "away_bullpen_fatigue",
      "effect": 0.009
    }
  ],
  "data_quality": {
    "lineups_confirmed": true,
    "starters_confirmed": true,
    "score": 0.94
  },
  "simulations": 10000,
  "simulation": "final_pregame",
  "model_version": "2026.07.04.1820",
  "generated_at": "2026-07-04T15:25:00-07:00"
}

Early access

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