The traditional way in which the defense is measured uses yards as the metric. Yes, I agree that points measure victory and defeat. However, yardage is a more fair method of measuring productivity, or the results of decreasing the productivity of the opponent.
Like you said, what you're calling "productivity" plays a comparatively small role in wins and losses. By far the two defensive metrics with the strongest correlation to wins are points allowed per drive and defensive passer rating. In PPD from 2006-09, Dallas ranked 19th, 14th, 14th, and 3rd. In DPR, 21st, 5th, 21st, 17th. There's certainly nothing about 2006 or 2008 that suggests those were top 10 defenses.
Why? Because points are influenced by beginning field position. For example, Would it be fair for the defense to be evaluated by points if there are a dozen opponent drives that season that begin on the Cowboys 30 yardline as a result of turnovers? In 2008 there were 9 such drives much higher than the NFL average.
You can't judge a defensive performance with an anecdotal tidbit. If you want to know how field position influenced points allowed from 2006-09, check our opponents' average starting field position from 2006-09, and be done with it. There were only 7 defenses whose opponent had
worse starting field position. In other words, field position helped rather than hurt our defense during those seasons. Total non-issue.
Putting it a different way, from 2006 to 2009, the Cowboys were in the top ten point differential 3 times.
Point differential isn't even a defensive stat. It's offense minus defense, which means Romo and the passing game played a huge part in that ranking.
Even if they were at 16, it would be sufficient enough to say they didn't suck which was a common accusation when claiming that Tony Romo had no help. In any case, three teams in the past ten years have won Super Bowls with defenses ranked 20 or lower in defense based on points.
And in every case, those defenses played better in the postseason -- unlike the Cowboy defenses you're talking about.
During the Romo era, the only playoff-caliber defenses in the regular season have been 2007 and 2009. Compare their
postseason performances with those of the three teams you referred to, using the stats that actually tell you something about defenses. In parentheses is how that playoff performance would have ranked that year in the regular season.
Defensive Passer Rating
2011 Giants 83.1 (15th)
2009 Saints 78.5 (12th)
2006 Colts 62.5 (1st)
2009 Cowboys 109.2 (32nd)
2007 Cowboys 132.4 (32nd)
Points Allowed Per Drive
2011 Giants 1.26 (2nd)
2009 Saints 1.79 (19th)
2006 Colts 1.00 (1st)
2009 Cowboys 1.88 (20th)
2007 Cowboys 2.63 (32nd)
When you take the average rank using the two best metrics, you can see how poorly Dallas' two "top 10" defenses played in the postseason, compared to other defenses ranked lower in the regular season.
Playoff Defense
2011 Giants 9th
2009 Saints 16th
2006 Colts 1st
2009 Cowboys 26th
2007 Cowboys 32nd
That's not to say the offense or Romo himself played well in those two postseasons -- they didn't and he didn't. But with those defensive performances, it wouldn't have mattered anyway.
