Success against the Dallas Cowboys on Sunday may come down to the New England Patriots' ability to prevent the big play.
Through five games, the Patriots have allowed 35 plays of 20 or more yards. That's already one fewer than the Pittsburgh Steelers allowed all of last season. It's also four more than any other team, and on pace to be historically high.
The Patriots are allowing 20-plus yards on an average of seven plays per game. That puts them on pace to allow 112 such plays this season. It's certainly early to be multiplying that over a full season, but doing so provides important context.
In 2004, the Kansas City Chiefs allowed 85 plays of 20 or more yards on their way to a 7-9 record. That's the most by a team in the past 15 seasons, according to STATS LLC. The Patriots are on track to surpass that by 27.
Despite their defensive issues, the Patriots are allowing just 23.4 points per game, which ranks 14th in the NFL. That's a big reason why, at 4-1, the Patriots have already matched the Broncos win total from 2010. But how much longer can the Patriots allow big plays while managing to keep opponents out of the end zone?
Certainly, the Patriots have been aided by an offense that is tied for the NFL lead with 33 plays of 20 or more yards. While that should get a test from a Cowboys defense that has allowed only 13, no one is truly concerned about the Patriots' ability to score.
New England's offense has masked the defensive issues. It's the reason why opposing teams still haven't run an offensive play while holding the lead -- the game-ending field goal against the Buffalo Bills marks the lone deficit of the season for the Patriots.
Consistent leads help explain the large number of yards allowed by the Patriots. After all, they can afford to allow opponents to drain the clock. However, those leads don't excuse all of the big plays. In 2007, a record-setting offense provided a near constant lead for the Patriots. Only 35 of the 526 opposing pass attempts came while the New England trailed. Yet, the Patriots' offense allowed only 39 plays of 20 or more yards, fourth fewest in the NFL. In fact, in 2007, the Patriots allowed only 14 pass plays over 25 yards. That number has already reached 20 this season.
So what's led to the Patriots' susceptibility to big plays? It's primarily an issue of pass defense. Of the 35 plays of 20-plus yards, 32 were passes. That's six more than any other team.
The problem starts with where opponents are catching the ball. Rather than yards after the catch or poor tackling, the big plays against the Patriots are the result of long throws. The average reception against New England is 7.5 yards from scrimmage, the third most in the league.
On passes thrown more than 10 yards, opponents are 40 of 69 for 934 yards. That 58.0 completion percentage, second highest in the NFL, is alarming when compared to the league average of 47.2 percent.
Not even the most conservative defensive approach is designed to allow 20-yard passes. No one would mistake the 2010 Patriots for an elite defense, and even they only allowed 19 such completions.
How did a bad pass defense get even worse in 2011? Failure to pressure the quarterback has played a role, but that was also the case last season. Another key appears to be turnover at safety, where the Patriots have struggled to replace Brandon Meriweather and James Sanders, an issue amplified by Patrick Chung's injury. Sergio Brown, James Ihedigbo and Josh Barrett -- a pair of undrafted free agents and a seventh-round pick -– haven't successfully filled that talent void.
How rare is it for a cornerback to record that many tackles? Over the past 20 seasons, it has only happened once, according to STATS LLC. In 2003, Antoine Winfield had 109 tackles for the Bills. Over the last 20 years, Ricky Reynolds' 85 tackles in 1995 are the most by a Patriots cornerback.
All of these numbers are of particular concern against the Cowboys. Despite already having their bye, the Cowboys are tied for third in the NFL with 23 passes of 20 or more yards.
This season, Romo is 8 for 14 for 333 yards on passes thrown over 20 yards. He's shined on deep passes to the right side, where the Patriots have been most susceptible to big plays. On throws of over 20 yards to the right side of the field, Romo is 5-for-8 for 201 yards and two touchdowns. Only Cam Newton has more such completions.
Those numbers should be troubling to the Patriots, particularly given the fact that Miles Austin has missed two games. Among active players with at least 150 career receptions, Austin's 16.2 yards per catch ranks fourth in the NFL.
Austin, who is expected to return on Sunday, caught four touchdowns in the Cowboys' first two games. That tied a franchise record set by Frank Clarke in 1962.
Along with Dez Bryant, Austin gives the Cowboys a pair of deep threats. That will provide the Patriots with the ultimate test in preventing big plays.
Jeremy Lundblad is a senior researcher with ESPN Stats & Information. He provides statistical analysis for ESPNBoston.com.