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Is the Pats' D a Super Bowl dealbreaker?

Posted by Andrew Mooney  October 29, 2011 12:53 PM

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Pack away your foam fingers, head south for the winter, and tell Pat Patriot he’s free to spend his weekends however he pleases. According to a CSNNE interview with Kerry Byrne from Cold Hard Football Facts, it is “statistically impossible” for the Patriots to win a Super Bowl if their defense continues to play at their current substandard level. Good season, boys – we gave it our best.

Before we proceed, a word on hyperbole: a statistical impossibility implies that the probability of an event’s occurrence is zero – as in, under no circumstances could this event occur on planet Earth. The probability of the Rams playing the Dolphins in this year’s Super Bowl is not zero. The probability of John Lackey pitching a perfect game with his left arm is not zero.

All quibbling aside, the Patriots’ defense has certainly been a cause for concern, ranking last in the NFL in yards per play and yards per game, though, they do maintain a solidly average 16th in scoring defense. Is Byrne on the right track? How unlikely is it for a team with a defense as porous as the Patriots’ to make a deep run in the playoffs?

Here’s a look at all the Super Bowl champions since 1992, plotted according to their season ranks in offensive and defensive efficiency – measures which record the results of every play during a season, adjust for strength of schedule, and compare the figures to those of a league average team – taken from footballoutsiders.com. Though the sample size here is too small to reveal any robust statistical conclusions, the plot can yield a few practically significant insights.


It’s difficult to win a championship without an elite unit on at least one side of the ball. All of these teams except two possessed either a top-5 offense or a top-5 defense. Yet it is possible to win a Super Bowl when one of these facets is well below average. The 2006 Colts won it all despite a 25th-ranked defense, while the 2000 Ravens took home their rings on the strength of Trent Dilfer and a mighty 23rd-ranked offense. However, only three teams managed the feat with a defense ranking in the lower half of the league.

In Byrne’s defense, none of these teams’ defenses ranked as low as New England’s, currently 28th in defensive efficiency. But remember that the Pats are only six games into the season. The extreme degree of their poor performance may simply be an aberration that will diminish as the season wears on, regressing toward more moderate results.

The Pats meet the criterion of one exceptional unit; their offense is tops in the NFL in terms of efficiency. Even if the defense doesn’t improve significantly, the ’06 Colts provide a good parallel – their defense rated about one standard deviation below the league mean efficiency that season, approximately the same position the Patriots find themselves in now. And in each case, the offense usually had something to say about the final result.

So while a poor defense hampers a team’s chances at a Super Bowl, it does not render them nil. It’s certainly statistically possible that the Pats win it all, even with a defense playing this poorly. In fact, if you asked the folks offshore, or in Vegas, they’d tell you it’s not much of a long shot – the Pats are 4/1 favorites to win the Super Bowl on sportsbook.com.

There’s just no quantifiable measure of the likelihood of winning a championship, so categorical predictions don’t carry much weight. In the playoffs, anything can happen. It would have been much more justified to talk about the impossibility of the 2001 Patriots winning a title after Tom Brady stepped into the huddle for the first time – they weren’t among the best in the league on offense or defense. Let’s just not talk about the other outlier on the plot: the ’07 New York Giants.

This blog is not written or edited by Boston.com or the Boston Globe.
The author is solely responsible for the content.

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Stats Driven is powered by David Sabino, who over the last two decades has been a source of statistical analysis on the pages of Sports Illustrated, New York Times, and Chicago Tribune. David has written about all seven recent Boston-area championships for Sports Illustrated Presents commemorative issues, was the creator of such long time features as SI’s Player Value Ranking, NBA Player Rating and long running fantasy football and baseball columns.

He has also authored or made contributions to many books, including the Sports Illustrated’s 100 Fenway: A Fascinating First Century.

Now living in Marblehead, he’s focusing his attention on the Boston sports scene, specifically delving into the numbers affecting the Red Sox, Patriots, Celtics and Bruins, with the goal of informing and entertaining real fans. You can follow him on Twitter at @SabinoSports.

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