The NFL realigned to eight divisions after the 2001 season. Since that time (three seasons), the AFC East has easily been the most dominant division in all of pro football. Take a look at the out-of-division records and winning percentage of the respective divisions:
AFC East 72-48 .600
AFC West 65-55 .542
NFC South 63-56-1 .529
AFC South 62-58 .517
NFC East 60-60 .500
AFC North 57-62-1 .479
NFC West 51-69 .425
NFC North 49-71 .408
One may think that New England has wind-aided the division, however all four AFC East teams have winning non-division records over this time period:
New England 23-7
NY Jets 17-13
Buffalo 16-14
Miami 16-14
To be fair, when assessing the Bills performance over the last few years, one should keep in mind that perennially we play in the toughest division in football.
Interestingly, in the last three years, the division has had only one wild-card entrant (this year's Jets).
Could you imagine if Indy was still in the division?