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Patriots offense and special teams are masking defensive deficiencies

The Patriots defense benefits from the best field position in the NFL.

When detractors of the New England Patriots want to highlight a weakness in the defense, they’ll point to the 21st ranked third down defense. Opposing teams have converted 40.9% of their third down attempts against the Patriots, which is almost 10% worse than the 1st ranked Miami Dolphins (31.5%).

“Every once in a while, you convert a long-yardage situation, but that’s hard to do in this league,” Patriots head coach Bill Belichick said on Monday. “Every once in a while there’s a team or two in the league that is above the averages on third-and-10-plus, or third-and-eight-to-10 or whatever the breakdowns are, but honestly, that usually doesn’t last too long.”

But there was one drive in particular against the San Francisco 49ers that caught my attention, and Alec Shane has written about it this week.

With 9:13 left in the second quarter, the 49ers led a 9 play, 92 yard drive that resulted in a touchdown. There was not a single third down play on that drive and only three second down plays. This is an example of a terrible, awful, no good, very bad defensive drive, but it doesn’t affect the third down defensive stats.

The whole point of the defense is to prevent the opposing team from scoring points. The Patriots defense has been one of the best in the league at this task, although they have received major assistance from both special teams and the offense to force opposing teams to start drives from a league-best 24.5 yard line. Belichick will always talk about playing complementary football and field position is a prime example.

Opposing teams have scored against the Patriots on a mere 31.2% of drives in 2016, the 6th best rate in the league- behind the Ravens, Rams, Cardinals, Eagles, and Seahawks. Opposing teams have averaged 6.62 plays per drive, the 8th highest mark in the league- although the Seahawks defense ranks 2nd with 6.89 plays per drive.

It’s difficult to isolate the performance of a defense without factoring in field position granted by the offense and by special teams, and there are certain stats that are skewed based upon defensive strategy (plays per drive).

The best way to compare the Patriots defensive performance to the rest of the league is not by a head-to-head comparison of points or yards allowed, but perhaps by the Expected Points model (EPA). EPA compares the performance on an individual play based upon historical averages- if a defense performs better in a certain down and distance than the league average, then the defense receives a positive grade.

There are only seven defenses that get the better of opposing offenses on a weekly basis: the Cardinals, Broncos, Vikings, Eagles, Ravens, Chiefs, and Texans. The Giants, Chargers, Seahawks, and Rams are pretty close to neutral, too.

The Patriots rank 17th, sandwiched between the Steelers and the Bears. Outside of the shutout performance against the Texans, the only times the Patriots defense got the better of the opposing team was against the Charlie Whitehurst-led Browns and the Landry Jones-led Steelers. The defense was considered neutral against the 49ers.

But the defense has been bad in all other games. They’ve given up crucial third-and-long conversions, or they allowed chunk plays, or they just couldn’t slow down the opposing team.

The Patriots third down defense isn’t the best way to counter the apparently elite status offered by average points against. But a combination of excellent special teams and a field-flipping offense has masked the apparent situational deficiencies of the defense, providing the defense with more room to make mistakes.