In order to look at an NFL team as a disappointment, there had to be a certain level of expectations to begin with. Those expectations could come from how the team finished last season, offseason changes or additions that were highly touted, or some combination of the two.
I'm sure there were some Miami Dolphins fans who expected better from their team so far, but since they kept head coach Tony Sparano and QB Chad Henne, they are about where we thought they were.
On the other end of spectrum are the Philadelphia Eagles. After winning their division and making the playoffs last year, then having the type of offseason they had (player additions), there is much expected of the Eagles this year and they aren't delivering.
So now that I've tried to explain my definition of "disappointment," let's look at 10 teams who are doing just that.