In the halcyon days of my youth, I was quite a formidable baseball player and spent a large part of my free time in the 80s playing or watching baseball. Today, I still watch the occasional occasional baseball game, but I have to keep my laptop close at hand in order to look up all the fancy stats that are being used in the game today, and which I'd never heard of in my youth. OPS, ISOP, SECA? Baseball has sure come a long way statistically with Sabermetrics and Moneyball.
In football, though the game has undergone significant changes over the years, the stats we use haven't changed much since the legalization of the forward pass in 1906. I could watch a football game with my 75-year old dad - who last watched a live football game in the 80s, and still thinks Dan Marino is the greatest football player ever - and my dad would still understand every single stat they put on the screen. And whether that's a good thing or a bad thing doesn't really matter. That's just the way it is.
Football is still very much dominated by volume based stats like total yards, points, number of completions, number of touchdowns and the like. Perhaps football fans and broadcasters are still traumatized by the introduction of the much misunderstood passer rating over 40 years ago, which remains one of the few efficiency measures being broadly used today.
While the major networks and many people who are paid to report about the NFL would have you believe that what matters is how many yards you accumulate, this is not in fact true. Volume stats do not correlate to victory. But efficiency stats do. How much someone passes or runs for can make for nice anecdotal discussions in the context of fantasy football, but has next to nothing to do with winning in the NFL.
So it was with great delight that I read a recent report by Tom Cowlishaw of the Dallas Morning News, who writes about which stats Rod Marinelli uses to assess his defense:
When I talked to Rod Marinelli in training camp, he said there were only two sets of numbers he cared about for his defense: the Aikman ratings and turnovers.
The Aikman ratings are a set of efficiency numbers (like a passer rating, but they encompass more things). The Cowboys ranked 32nd in that last year as well.
The Aikman Efficiency Ratings were devised by - you guessed it - Troy Aikman, who was looking for a better way to rate offenses than the NFL’s "official" method of measuring offensive and defensive performance: yards gained or allowed. In 2006, together with Rick Odioso, a statistician for Fox Sports and Jim Henzler, a senior analyst for Stats Inc., Aikman created the formula for the Aikman Efficiency Ratings (A.E.R.), which combines seven stats in five categories that Aikman believed offered a truer picture of offensive and defensive strength.
The exact formula used to arrive at the ratings was never made public, and remains proprietary to Stats Inc., but we do know what the seven stats are and how they are weighted in the formula:
|Adjusted Points||20%||Total points scored or allowed minus points on returns and safeties|
|Turnovers||20%||Turnovers allowed on offense or turnovers generated on defense|
|Red Zone Efficiency||20%||Percent of possible points - Number of points scored on red zone opportunitiesdivided by total red zone opportunities multiplied by seven|
|Yards Per Play||20%||10% - Yards per rush attempt|
|10% - Yards per pass attempt including yards on plays involving sacks.|
|First Down Achievement||20%||10% - Number of 1st downs gained or allowed|
|10% - 3rd down conversion percentage|
Before looking at the overall AER numbers, let's walk through the individual metrics for the defense after three weeks.
Adjusted Points: I don't know this for sure, but I'll assume that "returns" excludes not just punt and kick returns for a TD, but also interceptions and fumbles returned for a TD. Which would mean that of the 69 points the Cowboys have allowed over three games, seven points came from a pick six and another seven came from a fumble returned for a TD. The 55 remaining points ranks 12th overall in the NFL
Turnovers: The Cowboys have generated five turnovers, four interceptions and one fumble recovery, and rank a joint seventh in the league.
Red Zone Efficiency. The Cowboys opponents have had eight red zone possessions. At seven points per possession, opponents could have scored 56 points, but only scored 31 for an efficiency percentage of 55%, the sixth best value in the league.
Yards per play: The Cowboys are allowing 4.5 yards per attempt on the ground (22nd) and 7.5 yards per attempt through the air (22nd).
First down achievement. The Cowboys have allowed 58 first downs, the 10th best value in the league. Of note, the Cowboys have only given up three first downs on penalties, the fourth lowest value in the league (by far the worst team in the league are the 49ers, whose undisciplined play has led to 17 first downs allowed via penalty). The Cowboys' third down percentage looks much less impressive: with a 48.6% conversion rate allowed, the Cowboys rank 27th in the league.
While we don't know how the Aikman Efficiency Ratings are ultimately calculated, we do know that the stats above are combined into one single number and then adjusted against a league norm established over the last 10 years.
The resulting number is usually somewhere between 50 and 100, and the better the offense or defense, the higher the score on either scale. The average on offense is around 80 points, the average on defense is slightly below 70 points. Combine the two numbers and you get a value for overall team efficiency.
Here's what this year's Cowboys looks like versus last year's edition:
|Aikman Efficiency Rating||59.7||72.2||86.9||86.0||146.6||158.2|
Before you put this off as another set of esoteric stats with a public display of ignorance ("Hey, did you know that the team that scores more points wins 100% of the time"), consider that Rod Marinelli isn't the only coach who likes the Aikman Ratings.
"There are certain categories that we consider to be the most important," Tampa Bay coach Lovie Smith said earlier this month. "That’s why we go by the Aikman Ratings as much as anything, not the regular ones, because the regular one doesn’t tell you as much."
Week 3 obviously is still a little early to take the AER numbers as gospel. But as we get more data, the numbers will become more robust, which is why this is one of the stats I'll be watching closely this season. For now though, it looks like the Cowboys are headed in the right direction.
The ratings are published weekly, usually on Wednesday, and you can find them on the homepage of Troy Aikman Enterprises.