You missed by minutes. Find out why, from your own data.The Marathon Autopsy runs six failure modes against your race and your block, names the one that cost you, rules the others out with your numbers, and tells you the two things to change. Not a plan. A verdict.You know the number. 3:02 when you wanted 2:59. What you do not know is why, and every answer you have been given is a guess. Too hot, went out too fast, more gels, more long runs. All plausible, none checked against your splits. So you change three things at once and sixteen weeks later you still cannot say what worked.One verdict, not a menu. Six causes scored against your own race, the top one named, the rest ruled out with your numbers.Goal reality check. Tells you whether the goal was ever inside your fitness.Two changes only. Exactly two changes for the next block, and what to leave alone.Next-attempt projection. Projected finish on conservative, realistic, and best-case scenarios.Worked example included. 3:00 goal, 3:02:55 finish, verdict under-fuelling 90/100, every number visible.The science, explained. 12-page PDF; every threshold in the workbook is editable.Three bonuses. Strava/Garmin data prompts, a weekly on-track review routine, and a Race Week Checklist workbook.Just a file. No login, no subscription. Opens in Excel, Numbers, or Google Sheets.