Here's a slightly old (but very good) analysis of the difference in competetive balance between the NFL and MLB.

It reminded me of my theory which I came up with at Foxwoods that one could make money betting on the 10 worst teams in the NFL to make it to the next years superbowl, since it happens so often. (Credit where credit is due: I was inspired by this article written by the Tuesday Morning Quarterback.) So I decided to check this out. If you look at the betting lines for AFC and NFC championships at, say, this site you will see that the 5 worst teams in each division have odds pretty close to 25-1 against (for some bizarre unknown reason the bills are 16-1, but the others are about this or higher). So let's say we bet on the 5 worst in each division to make the next year's superbowl. Let's take the past 6 years as the recent era of parity (beginning with the end of the late cowboys/49ers dynasties). $1 on each of the 10 worst teams for 6 years costs $60. Now in that time there have been three teams whose records were in the worst five to make it to the superbowl: the 2001 Patriots, the 1999 Rams, and the 1996 Patriots (all 6-10 or worse). (Two other teams made at after being 7-9: the 2000 Giants, and the 1999 Falcons. Two teams made it after being 8-8: the 2000 Ravens and the 1999 Titans. The remaining five teams were coming off winning records.) Thus one would have made at least $75 on those bets. Therefore one would have made over a 25% profit, which is darn good. In reality several of those teams were particularly bad (for example st. louis) and one would have made a lot more.

In summary, bet next year on the Chargers, Chiefs, Jaguars, Bengals, and Texans to win the AFC and on the Panthers, Lions, Cowboys, Vikings, and Cardinals to win the NFC.

(See this site for the records of every team each year. See this site for superbowl teams and scores. Note that the superbowl takes place in the year after the season, so the 2001 Patriots won the superbowl in 2002.)

(This author does not encourage betting, and does not take responsibility for anyone's losses following this scheme, nor for the legality of anyone actually making these bets.)