I don't think your numbers are correct, unless you're counting the remaining games too.
But yeah it's simple. The SOS criticism to date is dumb.
Of course Dallas has a weaker schedule-- they've dished out 10 losses for their opponents.
That means their opponents are going to appear weaker AND their opponents are going to have a huge boost in their SOS with Dallas on the ledger.
Meaning any league ranking of SOS is going to be heavily skewed because Dallas is good.
You can statistically show this is a real effect (weaker teams tend to have better SOS rankings). Chad Stuart, if I recall correctly, did it on his blog. That said, it is also statistically provable that strength of schedule is a significant factor in playoff wins, so those teams who actually played a tougher schedule (so far, Atlanta) tend to win more games than those who played a weaker schedule.
I have a formula I've used for some time, which relates the logit of the win probability to this formula: 0.668 + 0.348(SRS calculated strength of schedule) + 0.434(Playoff experience). I should be publishing new formulas soon, with data for playoff experience within the year, within two years, and within three years. The scalar term, which is not obvious, is playoff HFA.
I wish I had bet it in the Denver-Carolina Super Bowl. I'd have been much richer if I did.
D-