AFC South Advanced Stat of the Week: Indianapolis Colts

Nate DunlevyGuest ColumnistApril 17, 2012

Bethea is the one bright spot in the Indy secondary.
Bethea is the one bright spot in the Indy secondary.John Sommers II/Getty Images

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.

Today we look at the Colts, who had traditionally done very well in this number, but that was back when Peyton Manning ruled the roost. How did the 2011 Colts fare?

They were 31st in the league.

I'd say that was a fairly accurate indicator of their success.

The Colts were a cataclysm at quarterback, ranking 30th in team passer rating. They also fielded one of the worst secondaries in the league, ranking 31st in defensive passer rating. The net result is a PRD of minus-31.7.

So, who has the No. 1 pick in the draft again?

You got it: the Indianapolis Colts.

None of this comes as a shock to even the most casual fan, so what can we learn about the Colts' road back to respectability from this stat?

First, Andrew Luck alone should help, but not right away. The Colts had a team passer rating of 72.2 last year. In the last 30 years, 30 rookie quarterbacks have had at least 300 passing attempts. Only half of them posted ratings better than 72.2, and only seven were better than 80.0. The good news is that four of those seven happened since 2008 (Dalton, Flacco, Ryan and Newton).

Still, the odds are against Andrew Luck improving the Colts' offensive rating much in year one.

The defensive half of the gap falls to Chuck Pagano. He's a career secondary coach who has always excelled at coaching up defensive backs. He has his work cut out for him. Even a relatively massive improvement of 15 points would still have the Colts in the bottom 10 in defensive passer rating.

Can the Colts post a big improvement in wins in 2012? It would take massive improvements in both phases of the passing game to pull it off. Hope is still probably a year away for Colts fans.