First of all, great to see you back. Sincerely.
To me it is all relative. The woman I will spend the rest of my life with grew up in Canton Ohio. To her, this was an incredibly successful season. The team she grew up rooting for not only won a playoff game for the first time in 26 years (ironically, when Belichick defeated Parcells and the Pats, they also did it by beating their close nemesis and arch rival (Pittsburgh). As an added bonus, her far distant #2 team won the Super Bowl (we have lived in the Tampa area for many years).
For a team like Green Bay it is a disappointment: you finished first in your conference, but didn't make it to the Super Bowl. Same goes for the Steelers, after beginning 11-0 and then losing five of their final six games. Other teams taking a step back after being in the playoffs: Texans and Eagles, for example - very disappointing.
In the preseason prediction thread, I went with the Pats going 7-9, so I wasn't surprised on the final outcome. My thought was that the defense would be really bad due to all the losses on defense to free agency, but that wasn't that big a deal. While I knew the offense would take a step back, I did not expect it to be as horrific as it was; that was most certainly disappointing.
I suppose my level of expectation is far lower than most. Whatever team you root for, you are betting on one horse versus a field of 31 other ponies. To expect to win it all even half the time is preposterous. Statistically in a 1:32 cycle, a fan should reasonably expect his team to win it all three times over an 80-year life expectancy.
As a fan, I've been playing with house money for quite some time. Losing one round at the table by going 7-9 is no big deal at this point for me.