[EDITOR’S NOTE: this is a special guest contribution from Patrick Causey. You can follow him on Twitter: @PatrickMCausey.]

Back in 2012, the Pro Football Researchers Association dubbed net passer rating differential the “Mother of All Stats.” Stated plainly, net passer rating differential is the difference in QB rating between a team’s own quarterback and the quarterback it faces. If a team has a positive passer rating differential, its quarterback is consistently outperforming the opponent’s quarterback.

So why is this the “Mother of All Stats”? Because it’s a pretty damn good indicator of a team’s Super Bowl credentials. A recent study found that 56 percent of the NFL champions finished first or second in passer rating differential from 1940-2011. And over the last 15 years, 10 of the last 15 Super Bowl winners ranked in the top five in the NFL in net passer rating differential (22 of 30 Super Bowl teams did as well).

In other words, teams that ranked in the top 5 of net passer rating differential were approximately twice as likely to win the Super Bowl as teams ranked outside of the top 5.

The Eagles rank 5th in net passer rating differential. The Patriots rank 10th.

The easiest way to affect a quarterback’s passer rating, and thereby improve your net passer rating differential, is to get pressure on the quarterback. Per Pro Football Focus, the average passer rating last year fell from 99.3 to just 64.6 when the QB was under pressure.

And therein lies the Eagles’ key advantage in the Super Bowl: it has a deep and talented defensive line that should be able to wreak havoc on the Patriots offensive line and Tom Brady. The Patriots offensive line is just above league average, ranking 14th in pass protection DVOA, per Football Outsiders. But Brady has been sacked 35 times this year, which is the 9th most in the NFL, and his sack rate of 5.7% is tied for the 3rd highest rate in his career.

So the chances to get pressure on Brady will be ripe for the taking. Now, Brady has been brilliant under pressure this year. According to ESPN, Brady has a 111.3 QB rate under pressure, which is tops in the NFL. But his recent success against pressure might be a statistical aberration. Excluding this year, Brady has struggled when he was pressured by opposing defenses:

Statistics courtesy of ESPN Stats & Information.

These statistics coincide with the scouting report that has been on Brady for quite a while now. As one NFL scout recently told NBCSports.com: “If you can hit him early and often, it changes how he plays. He won’t step into throws with the same authority. He won’t scan the field like he usually does. That pressure has to come up the gut, too. If it comes off the edges, Brady still slides and steps up in the pocket as well as ever. But if it is coming through the center and guards, [Hello, Fletcher Cox] you force him to move laterally. He’s not throwing the ball as well that way, especially if he’s forced to go to his left (like most guys).”

Those sentiments were echoed by Ryan Clark, the former Steelers cornerback turned ESPN-prognosticator: “When Tom Brady gets pressure and when you’re man-to-man and bumping those guys and making it hard for him to throw, he sees ghosts.”

In last year’s Super Bowl, the Falcons pressured Brady on 44.7% of his drop backs through the first 3 quarters en route to building a commanding 28-3 lead. But their pressure rate dropped like a rock in the 4th quarter and overtime as their defensive line wore down. Brady was under pressure on only 20.7% of his drop backs as he spearheaded the most dramatic comeback in Super Bowl history. It was the same story in last week’s AFC Championship game, as the Jaguars elite defensive line wore down as the game progressed. Brady’s quarterback rating through three quarters, when the Patriots could muster only 10 points? 87.5. But during the 4th quarter comeback, Brady’s passer rating improved to 136.3.

Compare those outcomes to the Patriots Super Bowl losses to the New York Giants. The key to both games wasn’t sacks – the Giants only sacked Brady a combined 7 times in both games – it was pressure. In 2007, Brady was under pressure on 20 of 43 dropbacks, or 46.5 percent, per PFF. In 2011, Brady was under pressure on 43.4% of the time, or 23 of his 53 dropbacks.

The good news for the Eagles is that, like both Super Bowl winning Giants teams, they have an elite pass rush AND quality depth. That combination is a rarity in today’s NFL, where salary cap restrictions make depth a luxury most teams cannot afford.

Per PFF, the Eagles pass rush finished the year with 41 more pressures than any other team, and they were the only team to generate pressure on at least 40% of pass plays. They also led the NFL with 7 players with at least 20-pressures on the year: Graham (60), Long (51), Cox (50), Curry (47), Barnett (37), Jernigan (23), and Allen (21).

That depth was most evident last week against the Vikings. The Eagles pressured Case Keenum on 24 of his 50 drop backs (48%). Per PFF, Keenum was 11/22 for 108 yards, 1 TD, and 1 INT when pressured, including the game changing Patrick Robinson pick-6.

In other words, the Eagles defensive line is more like the Giants Super Bowl winning teams than they are the Jags or the Falcons. They have the benefit of rotating their defensive line like a hockey team, keeping their pass rush fresh so it doesn’t wear down as the game progresses. If the Eagles defensive line can get constant pressure on Brady, they have a good shot at winning the Super Bowl.