How big of a concern is Pats' defense?

In a piece now posted on ESPNBoston.com, Jeremy Lundblad of ESPN Stats & Information looks closer at the Patriots' defense. The headline reads, "How big of a concern is Patriots' D?"

This will be the first time in the Super Bowl era that a team finished last in yards allowed and made the playoffs.

Of course, the Patriots aren't just last in the NFL. They are on track to allow a historic number of yards. With one game still to play, the Patriots already have allowed more yards (6,175) than any team to make the postseason. The previous high belonged to the 1981 Chargers (6,136).

In the past 60 seasons, only the 1981 Colts allowed more yards per game than the Patriots have this season. That team finished 2-14 while setting the record with 6,793 yards allowed.

The Patriots would have to allow more than 600 yards in Week 17 to exceed that. Far more likely, the Patriots will become the second team in NFL history to allow 6,500 yards in a season. The 2008 Lions fell 30 yards shy of that during an 0-16 season.

If the Patriots allow just 135 pass yards on Sunday, they will surpass the 1995 Falcons for the most allowed in a single season.

Of the previous 37 teams to allow more than 6,000 total yards in a season, only four made the postseason. Already in 2011, we can add two teams to that list in the Patriots and Packers. Both the Saints and Giants could join them.

There's clearly a flaw in measuring defense by yards allowed. But that doesn't totally explain how the Patriots have pulled this off.

Lundblad then goes on to detail how the Patriots have posted a 12-3 record with such a defense, focusing on a few categories:

1. Offensive firepower

2. Turnovers

3. Bend but don't break/red-zone defense

On the final point, Lundblad delivers this nugget: Consider that they've allowed 86 plays of 20 or more yards. That's 10 more than any other team and the most for any team in the past 15 seasons. Yet, of those 86 plays, only five went for touchdowns. Last season, the Broncos allowed 84 plays of 20 or more yards. Twenty of those plays were touchdowns.