Only two teams in modern NFL history have put together perfect regular seasons. Only one has run the table through the playoffs, and that was nearly a half-century ago.
While the 5-0 Kansas City Chiefs and 5-0 Los Angeles Rams are 31 percent of the way to regular-season perfection, history suggests they have their work cut out for them.
In the 48 completed seasons since the 1970 AFL-NFL merger, 80 teams have started 5-0. Including the playoffs, 79 have eventually lost.
The Chiefs also started 5-0 last year, five years ago (2013) and 15 years ago (2003).