The NFL's extreme competitive parity, combined with the physical toll of a 17-game regular season, drives the 92% implied probability against an undefeated campaign. No team has achieved this since the 2007 Patriots, and recent seasons have shown even Super Bowl contenders like the Chiefs and Eagles routinely suffer losses due to injuries, divisional matchups, and rest disadvantages. Key factors include elevated injury risk to quarterbacks and skill players, grueling schedules for top teams, and the absence of a clear superteam capable of dominating all opponents. An upset-free run would require flawless execution, favorable health outcomes, and consistent performance across conference play.