Not so odd but here's the real story. I agree that if you can keep a good team with all the salary cap rules, you can have a streak until injuries and salary cap kills your team. In fact, one sports writer compared football after the 90's to major leagur baseball. http://www.thebatt.com/media/paper65...ww.thebatt.com
Roughly 10 years ago, the powers that be in the NFL instituted some rulebook changes under the title of "parity." Fans of the game are familiar with these changes - the salary cap, that limits the amount of money a tea can spend on its talent, and the scheduling rules which pit the previous season's winning teams against their fellow winners.
Ideally, these changes serve as a means of challenging the strong teams and strengthening the weak. But, in reality, they make it harder for teams to afford to keep their best players and punish teams for winning games by way of harder schedules.
In all the fuss to keep things evenly matched, the long-term effects to the game were not considered fully, and, as a result, the NFL has become the crapshoot that it is today.