The NFL's 17-game regular season creates steep obstacles to an undefeated campaign, with only the 1972 Dolphins achieving it in the Super Bowl era. Modern dynamics such as expanded free agency, frequent injuries, and league-wide parity make sustained perfection rare, as recent seasons show strong starters often stumbling in late matchups or against tough road opponents. Schedule strength, bye-week timing, and roster depth play key roles, with historical data revealing that even elite teams with favorable home splits rarely navigate every contest without a loss. Current trader consensus at 84% for No reflects these entrenched barriers, where any single injury or upset can derail momentum in a compressed playoff race.