Each week, Cade Massey, from the University of Pennsylvania Wharton School, and Rufus Peabody, a Las Vegas sports analyst, rank all 32 NFL teams based off a mathematical model that takes only on-field performance into account. In other words, the model is purely objective and ignores outside factors like personnel, coaching and motivation.

The professor and the gambling-sharp look at only four statistics to evaluate offenses and defenses—rushing, passing, scoring and how effectively the ball is advanced relative to down and...