Wins Over Average: Which NFL Quarterbacks Are Winning Games For Their Teams?

The Cowboys have played two games, losing one and winning one. If you were to read some of the headlines floating around out there - and gave them any credence - you could easily get the impression that it was Tony Romo all by his lonesome who lost the first game for the Cowboys and then went and won the second one all by himself.

The QB, whether you like it or not, is the only player on a football team who has a W/L record in his personal stats. But think back to the Jets game. Did Romo really lose that game, or did the Jets win the game? At first glance, this may sound like semantics, but it really isn't. Is the Cowboys current record only a result of Tony Romo's offensive prowess (or lack thereof), or was the defense an equally strong but perhaps more underappreciated driver of these results?

Today, instead of going with a totally subjective 'Tony Romo is awful/awesome' assessment, we take a more objective, stat-based approach to figure out which NFL quarterbacks are winning games for their teams, and which aren't. After the break, we look at 'wins over average' to understand which QBs, and by extension their offenses, contributed to wins for their teams.

'Wins over average' is a metric developed by Doug Drinen at Pro-football-reference.com (PFR) in a post on adjusting QB records. I've taken his approach and modified it slightly for this post.

The underlying assumption for 'Wins Over Average'  (WOA) is that it's a lot easier for a QB to win games when the defense holds the opponent to 10 points than it would be if the defense gave up 30 points. This is not rocket science.

What WOA does is it calculates a QB's winning percentage against a given bracket of points scored by the opponent (e.g, 0-10 points, 11-17 points etc.) and then compares how many games that quarterback won versus how many games an NFL average QB would have been expected to win.

To calculate WOA, we first need a baseline to determine what 'NFL average performance' looks like. For our purposes here we'll use the league average winning percentage in regular season games since 2006. In the table on the right I've crunched the numbers for all NFL regular season games since 2006, so that's 82 games for each of the 32 teams for a total of 2,624 scores, and I've formed five clusters by points allowed for which I've calculated the winning percentages for the offenses.

How to read the table: A QB (and by extension, the team) will almost always win the game when the defense holds the opposing team to ten points or less (432-27 winning record). The NFL average winning percentage is .941 against the '0-10' points bracket. The more points a team allows, the lower their chances of winning the game. When your defense allows 32 points or more, your QB's chances of winning a game are very low (.072 winning percentage, 31-400 record).

What separates the good from the merely average QBs is their ability to win games that an average QB would not win. And that is exactly what WOA measures. 

Tony Romo and Wins Over Average: Tony Romo has a record of 14-1 as a starter when the defense allowed ten points or less. The average NFL QB would be expected to win 14.1 games (15 games x .944 NFL average), so Tony Romo has -0.1 WOA in this points bracket. In the 11-17 points bracket, Romo has a 10-3 record, an average NFL QB would be expected to win 9.2 games (13 games x .711), Romo therefore gets 0.8 WOA. Across all brackets, Tony Romo has accumulated +6.0 WOA as per the table on the right.

So statistically, over the course of his five years as a starter, Tony Romo accounted for six more wins for the Cowboys than an average NFL quarterback would have. At first glance, that doesn't sound like all that much, so in the next step we'll try to understand how that number compares to other quarterbacks around the league.

Before we do that though, keep in mind that when I say "Tony Romo", I'm actually talking about Miles Austin, Jason Witten, Felix Jones, Jason Garrett and many more people who make up or influence the Dallas Cowboys offense. Quarterbacks don't win or lose games, teams do. But if quarterbacks are going to be measured by wins, let's at least make sure we understand the quality of those wins.

In the next table, I've listed the thirty active (or relatively active) quarterbacks with the most career regular season starts. I've calculated their Wins Over Average in the same way I've calculated Romo's numbers above. Since every QB on the list has started in a different number of games I've added an additional column in which I divided the WOA by the total number of regular season games started. This should allow for a better comparison of the quarterbacks regardless of how many games they started.

Career Wins Over Average by Quarterback, regular season games.

Couple of observations about the table on the right, starting with Tony Romo. Romo's numbers obviously took a hit in the 2010 season. If I were to exclude his 2010 games, Romo would have an 11.3 WOA percentage, which would easily place him in the top 5 of active NFL quarterbacks. But 2010 happened, and we can't just pretend it didn't. Similarly, if we were to exclude 2010 from Michael Vick's numbers, his WOA would drop to an even more pedestrian 3.2%.

At the end of the day, Tony Romo wins games for the Cowboys. And he wins more games for the Cowboys than most other QBs win for their teams. That's really all I need to know - but please read on anyway.

No real surprises at the top, where Tom Brady and Peyton Manning are in a class of their own. The only surprise here is that this is yet another stat in which the two are very close to each other.

A clear surprise for me at the top is the 3rd-ranked Matt Ryan. This may be obvious to people who watch the Falcons closer than I do, but the numbers suggest that Ryan has been winning a lot of games for the Falcons. The Falcons have stumbled out of the gate a little this year, but with the recent additions to their offense, Ryan's numbers should only get better. Oh, and for anybody still caught up in the Ryan vs. Flacco debate, move along to something else.

Two guys I didn't expect so far up the table are Eli Manning and Vince Young. For all his awkwardness, sub-par completion percentage and tendency to throw interceptions, Eli does find ways to win games for the Giants. As for Vince Young, the fact that he is now merely a backup - despite his W/L record and WOA percentage - is probably the biggest indictment for judging QBs by their W/L record, as I'm sure the Titans' Chris Johnson would agree.

It's a bit surprising to see the latest Super Bowl winner so far down the list. Aaron Rodgers' WOA is solid but not spectacular. The key reason for this is that his W/L record against teams that score 18-24 points is a decidedly unremarkable 6-7. This is the point bracket where every single one of the WOA leaders gets the bulk of his WOA. Rodgers is -0.3 in that bracket. In other words, his performance (and that of his offense) is below average in those situations.

Obviously, there are many ways to evaluate a QB's performance. This is one way that may be slightly off the beaten path, but taken with other valid metrics out there, it helps solidify an overall picture of today's NFL quarterbacks, and raises a question or two.

Just don't get me started on QBR.