When the New England Patriots strode onto the Bermuda grass of University of Phoenix Stadium on Feb. 3, 2008, the spectre of history was waiting for them. The Patriots had, to that point, won all 18 of their games during the 2007 season and were a Super Bowl victory away from the NFL’s first undefeated season since 1972.
Although we didn’t exactly know it at the time, New England carried one additional bit of history into that evening: the single highest Elo rating achieved by any professional football team, ever.
The Elo rating, as longtime FiveThirtyEight football readers will recall, is our pet metric for evaluating a team’s skill level at any given moment. Elo is hardly the only power rating in town, but we like it because it’s a relatively simple algorithm1 with an elegant, endlessly customizable2 design that makes the most of the information it receives.
It’s also easy to compute for historical seasons, which is what my colleagues Reuben Fischer-Baum and Nate Silver did Wednesday in an interactive graphic that maps out the complete history of the NFL.3 It’s intended to help visualize the jagged peaks and valleys of a franchise’s performance from week to week and season to season. And no matter how you measure it, the zenith of that 2007 Patriots campaign is our interactive’s Mount Everest.
While the average NFL team has an Elo rating of roughly 1500 (and the top team in any given week floats around 1700), midway through the 2007 season the Patriots became the fifth4 team to ever crack an Elo of 1800. On the path to the Super Bowl, they’d eventually pass the 1983 Washington Redskins (peak Elo: 1800), 1968 Baltimore Colts (1803), 1942 Chicago Bears (1804) and the 2004 version of themselves (1817) to set the all-time record Elo rating of 1849 after their victory in the AFC championship game.
Peak ratings aren’t everything, though, and the 2007 Patriots are an example of why. Despite possessing the best Elo ever, New England lost Super Bowl XLII to the New York Giants, sending their end-of-season rating tumbling to 1824. It’s still the best season-ending Elo ever, but it shows why a balance must be struck between the apex of a team’s performance and a consideration for its play outside of its best stretch.
That’s why, for our master ranking of the best Elo seasons ever,5 we computed each team’s season-ending Elo6 and its season-long mean Elo7 in addition to its peak rating. The teams in the table above are ranked by the column labeled “blend,” which simply takes the average of the three measurements to get a more holistic picture of a team’s quality. (You can, of course, sort by any of the three component metrics as well.)
GRAPHIC: We calculated game-by-game Elo ratings for every team in NFL history — more than 30,000 ratings total. Explore how your favorite team has done over the years »
Despite losing the Super Bowl, the 2007 Patriots rank first all-time by Elo — in fact, they’re the only team with a composite rating higher than 1800. The 2004 Pats are right behind them in second place; those two editions of the Patriots are the only teams in pro football history to end a season with an Elo of more than 1800. Many readers will doubtless slap an asterisk on their accomplishments, what with Spygate, Deflategate, Radiogate and the like. But in the sense of pure statistical dominance, Elo says the best Patriots teams have no historical equal.8
But as the 2007 Pats’ Super Bowl loss suggests, the top Elo teams of all time aren’t invincible. Four of Elo’s top 10 NFL teams of all time failed to win their league’s championship. That figure is zero in the NBA, bolstering the adage that the best team wins more often in basketball than it does in football.
Are football and basketball so different, though? Both sports’ Elo formulae are similar, as are the ranges of team Elo ratings. Research also suggests that individual basketball and football games convey roughly the same amount of information about the relative quality of the two teams playing. The only real difference is that the NBA’s regular season is more than five times as long as the NFL’s — and its playoffs are best-of-seven instead of one-and-done — so luck tends to be much less of a factor.
That’s why the NBA’s best teams usually have win totals pretty close to what Elo would predict if they played 82 more games against the same schedule. This wouldn’t be the case if either sport’s best teams were asked to play only 16 more games (their records would likely be several games closer to .500 the second time around), which is why NFL records are always noisier than the underlying talent that powers them.
(Then again, maybe that just means there is no greatest team ever.)
Either way, you can relive the glory days of the past and check your favorite team’s progress in the interactive this season, whether you’re hoping for another top 100 entry from the No. 1 Patriots or waiting patiently for the 32nd-ranked Buccaneers to return to greatness.