For starters, let's look at the AFL: Pats, Bills, Oilers/Titans, Dolphins, Jets, Bengals, Chiefs, Broncos, Chargers, Raiders, and Dolphins
That's 11 teams. Playing straight odds they should now have represented the AFC/AFL in 77% of Super Bowls and won roughly 38% of them. They are keeping up on appearances with 77% on the nose but their win total is a measly 25%. Back-to-back AFL wins have only happened 4 times. But to their credit, during the NFC domination of Super Bowls (XVI - XXXI) the AFL fielded a pummeling block every year but one. For the 2nd straight year and 4 out the past 5 years, an AFL team did not even win the AFC. The winners of the 4 in question were all former NFL teams given to the AFC to even the numbers out (2 for the Steelers and 2 for the
Now it's time for the pre-merger NFL teams: Cowboys, Redskins, Saints, Eagles, Browns, Giants, Cardinals, Steelers, Rams, Colts, Falcons, 49ers, Vikings, Packers, Lions, and Bears
The NFL math gets a little hairy because you have to account for the 3 teams that could potentially take an AFC spot any given year, how to handle the Ravens/Browns, and you have to account for the Seahawks. For our purposes, I'll go ahead and count the Ravens as an AFC expansion and the Seahawks are an expansion no matter how you slice it.
Statistically, the pre-merger NFL should represent the NFC 40 times and the AFC 8 times. Among those appearances, they should take home the title 23 times. They have represented the AFC 8 times on the nose and the NFC 42 times. They are +7 on their win total with 30 total Super Bowl wins for pre-merger NFL teams. (That's assuming the foregone conclusion that a pre-merger NFL team will win when the pre-merger NFL Saints play the pre-merger NFL Colts in Super Bowl XLIV.)
So for any fan of the old guard AFL teams who tries to tell you that merger was a merger of equals, you are now armed with the knowledge that the AFL-NFL merger was anything but. The NFL merely swallowed up some inferior franchises to flesh out their ranks faster and easier than they could without the merger.