Better defense: 2015 Broncos or 2013 Seahawks?

The Broncos' defense is fresh off one of the greatest playoff runs of all time, holding three of the top four scoring offenses to an average of 14.7 points per game in the playoffs.

Obviously the Broncos' defense carried them through the postseason, but was their season, as a whole, the best we’ve seen in the PFF era (2007–2015)? Let’s dig through the numbers and compare them with the reigning top defense, the 2013 Seattle Seahawks.

Above are the unit grades for each team, as well as how those grades rank among all NFL defenses of the PFF era (again, 2007–2011 only). The Broncos clearly have the advantage in run defense, while the Seahawks' secondary was unrivaled. The pass rush for each team was outstanding, so we’re going to have to dig a little deeper to get a better picture.

The league average for points per game for 2013 and 2015 was 23.1 points per game. When we look at how often both defenses allowed more than that league average, the Seahawks come out ahead. Seattle only gave up more than 23.1 points twice in 19 games, while the Broncos did it four times. The Seahawks yielded just 20 touchdowns on 990 plays compared to 29 for Denver on 1,033. At their worst, they both gave up 34 points, but the problem with using points allowed as a measuring stick is the fact that it can be impacted by their respective offenses.

When it comes to yardage, the 2015 Broncos outshine the 2013 Seahawks. Denver never give up 400 yards of offense in a game, while Seattle did twice—both, however, gave up an average of 4.4 yards per defensive play. So, clearly Denver’s offense was negatively impacting their defensive scoring metrics at times.

With everything else seemingly a wash, we’ll look at when both defenses were at their very best—this is where the Seahawks really shine. In the 2013 season, Seattle held seven of their opponents under 10 points, while the 2015 Broncos pulled off that feat just once. They also held seven opponents under 250 total yards, while the Broncos only did that three times. And then, when you take the most dominant performance from each—which coincidentally both occurred in Super Bowls—the 2013 Seahawks once again have the edge. Seattle held the highest-scoring offense of all-time (the 2013 Broncos, coincidentally) to a measly eight points, 306 total yards, and scored as many points on their own as the Broncos did offensively in Super Bowl XLVIII.

There is no shame in being the second-best defense in the PFF era, but the 2013 Seahawks still reign supreme.