Sunday, November 8, 2020

An Average AFC East Team Probably Could Not Have Replicated the Patriots' Playoff Success

With the Tom Brady era over in New England, it's worth trying to determine how much of the Patriots' dynastic success was due to their membership in the subpar AFC East. As a coworker posed it, what kind of an advantage did the Patriots get from basically being a playoff shoo-in every year? With an average to above average team, making the playoffs over a 20 year span, how many Super Bowls would they expect to win?

Looking at their last 19 seasons (once Tom Brady became their starter), the Patriots made the playoffs 17 times, winning the division each of these times (the two seasons they missed, they lost the wild card on a tiebreaker). They won 30 playoff games, made the Super Bowl 9 times, and won 6 of them.

Getting in to the postseason 17 times certainly is a huge advantage, so to quantify this I estimated how the Patriots would have done as a "generic" playoff team, with the home field advantage they were granted every single time as the AFC East division winner. They never made the playoffs as a wild card.

As I found earlier, playoff home field advantage (4.35 PPG) is a bit higher than overall (2.41 PPG). Converting this to a win probability, between two evenly matched playoff teams, the home team would have win odds of 67.11%. When the Patriots were a 3 or 4 seed, they were guaranteed one home game; as a 2 seed, two home games; as a 1 seed, three home games.

I ran this math out over the past 19 years of the Patriots dynasty:

 Season MadePlayoffs MadeSB WonSB WonDivision ConfSeed Note OddsG1 OddsG2 OddsG3 OddsSB OddsWinSB OddsMakeSB ExpWins 2001 1 1 1 1 2 Won Super Bowl 100% 67% 33% 50% 11% 22% 1.5 2002 0 0 0 0 100 Missed Playoffs 0% 0% 0% 0% 0% 0% 0.0 2003 1 1 1 1 1 Won Super Bowl 100% 67% 67% 50% 23% 45% 1.8 2004 1 1 1 1 2 Won Super Bowl 100% 67% 33% 50% 11% 22% 1.5 2005 1 0 0 1 4 67% 33% 33% 50% 4% 7% 1.8 2006 1 0 0 1 4 67% 33% 33% 50% 4% 7% 1.8 2007 1 1 0 1 1 Lost in Super Bowl 100% 67% 67% 50% 23% 45% 1.8 2008 0 0 0 0 100 Brady torn ACL, MCL 0% 0% 0% 0% 0% 0% 0.0 2009 1 0 0 1 3 67% 33% 33% 50% 4% 7% 1.8 2010 1 0 0 1 1 100% 67% 67% 50% 23% 45% 1.8 2011 1 1 0 1 1 Lost in Super Bowl 100% 67% 67% 50% 23% 45% 1.8 2012 1 0 0 1 2 100% 67% 33% 50% 11% 22% 1.5 2013 1 0 0 1 2 100% 67% 33% 50% 11% 22% 1.5 2014 1 1 1 1 1 Won Super Bowl 100% 67% 67% 50% 23% 45% 1.8 2015 1 0 0 1 2 100% 67% 33% 50% 11% 22% 1.5 2016 1 1 1 1 1 Won Super Bowl 100% 67% 67% 50% 23% 45% 1.8 2017 1 1 0 1 1 Lost in Super Bowl 100% 67% 67% 50% 23% 45% 1.8 2018 1 1 1 1 2 Won Super Bowl 100% 67% 33% 50% 11% 22% 1.5 2019 1 0 0 1 3 67% 33% 33% 50% 4% 7% 1.8 Total 2.4 4.8 29.2

The "generic" playoff team in their position would have won 29.2 playoff games - very close to the Patriots' total of 30 (and this doesn't include 13 first round byes). But the Patriots way over-performed at the apex - the "generic" team would have made 4.8 Super Bowls and won 2.4 rings - which is still a massive advantage! Having an expected value of over 2 Super Bowls in just as many decades. But that would fall far short of winning 6 in 9 tries - which is how you get to G.O.A.T. status for both Tom Brady and Bill Belichick.