Jacksonville Jaguars Advanced Stat of the Week: What Happened to the D?

Nate Dunlevy@NateDunlevyGuest ColumnistFebruary 14, 2013

More awesome coverage from Aaron Ross.
More awesome coverage from Aaron Ross.Bob Levey/Getty Images

For once, something isn't Blaine Gabbert's fault.

The Advanced Stat of the Week this week is Passer Rating Differential.

Passer rating has scores of critics. The most common complaints are that it overvalues completion percentage, it has no opponent adjustment, it has no way of adjusting for game situation, it doesn't value running at all, it doesn't account for sacks or fumbles, it is ridiculously hard to calculate and it was scaled in the 1970s, making it notoriously useless for comparing quarterbacks of different eras.

Other than that, it's great!

Actually, I have always had a soft spot in my heart for passer rating. Aside from the fact that it correlates well with winning, it always seemed like the stat that Joe Montana led the league in, and that has to count for something, right?

I realize that I'm being uncharacteristically kindhearted to the deeply flawed and possibly useless number, but passer rating is here to stay and is still infinitely more useful than ranking teams and players by yards. Passer rating is so painfully mainstream that addressing it as an "advanced stat" would make a mockery of the holy name of advanced stats.

So, this week I'm going to tip my hat to our dear, lame old friend and address Passer Rating Differential.

Passer Rating Differential (PRD) essentially compares offensive and defensive passer ratings. One of the reasons I enjoy it so much is that the top eight teams in PRD all made the playoffs in 2011. It covers the gamut of teams from the Packers and Saints (great offensive passer ratings, mediocre defensive ones) to the Ravens and 49ers, who posted outstanding defensive numbers.

PRD shows us that it doesn't matter what combination you use to get the job done. Stopping the pass and passing the ball is the key to winning in the NFL.

The 2012 Jaguars were among the worst in the league at everything, but relax. All the blame isn't going to fall on Gabbert this time.

While Gabbert was the worst in the league in the important yards per attempt stats, his actual passer rating wasn't bad. Thanks to a low interception rate, the Jaguars actually improved in passer rating in 2012 over 2011.

Instead of moving forward, the Jaguars finished with the worst record in football.

The defense deserves the blame this time.

While most of the improvement in offensive passer rating was just cosmetic (a weakness of the stat itself), the defensive decline was pronounced. A year ago, the thought was that if the Jags could just get a little better on offense, they could finish near .500.

They got a little better, but the defense got a lot worse.

Once again the bugaboo was the yards per attempt. The Jags allowed almost the same completion percentage in 2012 as in 2011, but the passes went for more than a half yard more per attempt.

Injuries were the primary reason. Jacksonville lost two thirds of the linebacking corps before the season and battled secondary injuries all year long.

The Jaguars improved overall in PRD in 2012, but retained their terrible ranking overall.

Hiring Gus Bradley to fix the defense was a wise first step for the new regime in Jacksonville. Seattle was third in defensive passer rating in 2012, just a fraction of a point behind first-place Arizona.

If Bradley can work his magic in Jacksonville, they'll eventually march back up the PRD standings and more importantly, the division standings.