The New England Patriots defense is allowing a 101.0 passer rating against, the fourth highest in the NFL this season. (Jim Rogash/Getty Images)

The NFL season is half over and we are starting to see some teams separating themselves from the pack, in both good and bad ways. One of the most reliable indicators for separating the title contenders and pretenders is by looking at passer rating differential — the difference between a team’s passer rating and the collective rating of the team’s opposing quarterbacks. Its correlation to success led football stathead Kerry Byrne to dub it the “Mother of All Stats” during the 2012 Pro Football Researchers Association biennial meeting hosted by NFL Films. Since 2002, 22 of the past 30 Super Bowl participants had a passer rating differential among the top five best in the league, including 10 of the past 15 winners. The outliers among the eventual Super Bowl winners include the 2005 Pittsburgh Steelers (7th), 2007 New York Giants (24th), 2011 Giants (12th), 2012 Baltimore Ravens (12th) and the 2015 Denver Broncos (18th).

The average differential for a non-playoff team over the past 15 years has been minus-7.7, with a higher regular-season passer rating differential indicating the potential for a deeper playoff run. This makes complete sense: The NFL is a passing league, so success through the air while limiting opponents from doing the same should be regarded as a recipe for success.

Playoff results (2002 to 2016) Average rank of net passer rating differential Average net passer rating differential
Did not qualify 21st -7.7
Lost wild-card round 11th 7.1
Lost divisional round 8th 13.4
Lost championship game 9th 12.2
Super Bowl appearance 6th 18.9

By this metric, it is safe to believe the Kansas City Chiefs are still a Super Bowl contender despite two straight losses. Quarterback Alex Smith has completed a league-high 72.4 percent of his passes for 1,979 yards, 15 touchdowns and no interceptions for a 120.5 passer rating, highest in the NFL this season. The Chiefs’ defense, meanwhile, has kept opposing quarterbacks to an 88.5 rating, giving them the highest passer rating differential in 2017 heading into their Monday night matchup against the Denver Broncos.  The Seattle Seahawks, New Orleans Saints, Jacksonville Jaguars and Buffalo Bills round out the top five.

One team conspicuously absent from the top of the leader board is the New England Patriots. The odds-on favorite to win Super Bowl LII, the Patriots’ pass defense is horrid this season, allowing a 101.0 passer rating against, the fourth-highest in the league after the Oakland Raiders, Miami Dolphins and winless Cleveland Browns. That brings their net pass differential to plus-5.5, well outside what we would expect for a Super Bowl contender.

Yes, there is still time for the Patriots to figure out a way to defend the pass, but also consider this is a low point for the franchise, having produced a net passer rating differential below this year’s mark just two other times since 2002 — in 2005 (plus-3.7 differential) when they lost 23-17 to the Denver Broncos in the divisional round and in 2008 (minus-0.7) when they failed to qualify for the playoffs.

Other pretenders — those teams given odds of 20-to-1 or less to win Super Bowl LII by the Westgate Las Vegas Super Book as of Oct 24. —  include the Dallas Cowboys (20-to-1) and the Atlanta Falcons (14-to-1), who rank 17th and 20th, respectively, for net passer rating differential in 2017.

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