I found an interesting article on how the 2007 New England patriots weren't as "perfect" as one might think. It can come across as a personal opinion but they back it up with good analysis and statistics.
http://www.thefount.info/16-0isthenew15-1.html
"The top win total from the NFL the past five years has been, in succession, 14, 15, 14, 14 and now 16 games. Over the previous 23 years in the league, if you combine the best five teams' records overall you can scrape together a total that equals that many wins. Why has a sudden upswing in wins, punctuated by the unprecedented 16-0 performance by the Patriots this year, been seen for top NFL teams? Your Fount experts decided to get to the root of this question: Does 16-0 in 2007 mean what it would have meant two decades ago?"
That was interesting. They did fail to point out it was the Pats with 3 of those win totals (14, 14 & 16). While the division stunk in 2007, the rest of the Pats schedule contained 8 playoff teams.
I'd attribute a lot of the Colts and Steelers success over the same time period to the divisions they played in, as much or more than the Pats record.
I skimmed the article. Did they mention the decline of the NFC over that same time period?