Back in February, in a three-part series, we looked at the stat perhaps best correlated with winning the NFL - Cold Hard Football Facts’ Real Quarterback Rating Differential. It’s even better than the better known passer rating differential.
Let’s compare how passer rating differential (PRD) and real quarterback rating differential (RQRD) correlate with winning over the last five years. The percentages indicate how often the team winning PRD or RQRD won games over these years.
Let’s look at this another way. Where have Super Bowl opponents ranked under these two stats over the last five years?
|Year||SB Team||RQRD Rnk||PRD Rnk|
Of the ten Super Bowl teams since 2012, six have ranked first or second in real passer rating differential, two more have ranked fourth, and two have been 12th. Plus, all 10 teams have ranked as high or higher than they ranked in passer rating differential.
As you can see, real quarterback rating differential (RQRD) is a superior stat. It stands to reason that teams should strive to maximize their real quarterback rating on offense, and minimize the opponent’s real quarterback rating on defense to give themselves a better shot at the Super Bowl.
With that prelude, we looked at where the Cowboys ranked in this differential over the last several years. It is summarized in this table.
As you can see, the offense upheld its end of the bargain in 2014 and 2016 when it had a high-quality quarterback and dominant running game. But the defense has been consistently below average for the last five years. If Dallas could move into the top-10 or even top-15 in holding down opposing quarterbacks, it might well seize one of the top two overall slots in this metric and dramatically improve its odds of winning the Super Bowl.
The specific formula for calculating defensive real quarterback rating is not divulged by Cold Hard Football Facts, and their site is no longer active, so we will have to revert to defensive passer rating as a proxy.
What goes into the passer rating formula?
- Pass attempts
- Pass completions
- Passing yards
One way to look at the value of these factors is to look at them through a different statistical lens - adjusted net yards per passing attempt. That formula is pass yards + 20(TDs) - 45(INTs) - sack yards)/(pass attempts + sacks). The thing to note here is that a single interception negates slightly more than two touchdown passes. Sacks are not considered in the passer rating formula, but are considered in the defensive real quarterback ratings (as are quarterback fumbles), and are another way to weaken opposing passer numbers. Keeping opponents’ passes short, and reducing their completion percentage also helps to improve a defense’s rating.
With that in mind, where do the Cowboys need the most help? In 2016, the Cowboys ranked:
- 24th, with an opponents passer rating of 94.1. Denver ranked first, at 69.7, more than 5 points ahead of the next team, the New York Giants. 10th was Arizona, at 85.1. That suggests Dallas needs to reduce opponents passer rating by close to 10 points to get into the top-10.
- 17th in touchdowns surrendered, with 25. Denver led with 13. The Giants were second with 15. Tenth was the Chargers, with 21.
- 27th in interceptions, with nine. Kansas City led with 18. Tenth was Oakland, with 16.
- 31st in completion percentage, at 67.1%. Denver led with 55.4%. The Giants were third at 58.6%. Tenth was Seattle, at 61.6%.
- 13th in yards per attempt, at 6.9. Denver led with 5.8 Y/A. Tenth was Arizona, at 6.8 Y/A.
- 26th in yards, at 4167. Denver led with 2972. Tenth was the Rams at 3732. Dallas surrendered more total yards because they faced more pass plays than most teams.
- 13th in sacks, at 36. Arizona led with 48. Tenth was Pittsburgh, with 38.
Given these rankings, the keys to keeping opposing quarterbacks ratings down are:
- Lowering a near league-worst completion percentage against.
- Increasing the number of interceptions.
- Cutting the number of passing TDs.
- Improving the sack rate.
We have already written about the Cowboys prospects of improving turnovers and increasing sacks. There is hope for improvement in both areas, but no certainties.
As for reducing the other numbers, there is no comprehensive data on the passer rating against each defensive back, which might allow us to estimate if the new Cowboys DBs are likely to be better than the ones they are replacing.
There is spotty data, however. For example, at one point in October last year, Jourdan Lewis had given up only seven yards to opposing quarterbacks. At the end of the year, he had the best passer rating allowed over the last three seasons, at 47.1. PFF’s player comparison was Chris Harris of Denver, who just happens to be PFF’s highest-rated cornerback last year. If Dallas got anything close to a Harris clone in the third round, they should be jumping for joy.
The New York Giants last year spent tens of millions on free agents for their defensive line and secondary, and with upgraded play from holdovers, they dramatically improved their ranking in this stat. The Cowboys have taken a cheaper route, by attempting to upgrade through the draft. Will it work? This is a critical issue going into 2017. That’s why this is burning question number 3.