Fair question, and, before I answer, let me say that I still think we win the AFC East this year and that "anything can happen" in January.
Now, to your question.
Every offseason, the Pats try to balance long term (next two to five years) needs and short term (winning a ring this year) needs. I'm sure that you and I would agree that they've done a better job of this than any team in the NFL in recent history. The facts speak for themselves.
So, for the Patriots, as far as I can see, "rebuilding" means putting more of an emphasis in a given offseason on the "two to five year" horizon than on the "this year" horizon. It doesn't mean that they don't want to be competitive this year, it just means that they're not putting the primary emphasis on loading the guns, as they did when they added a Dillon or a Colvin in different offseasons.
I can't look at this offseason and draw any other conclusion than that, this offseason at least, the Patriots have placed the primary emphasis on looking down the road a couple of seasons. They have allowed key parts of the championship runs to leave town when they all still had varying levels of gas in the tank rather than pay a three to five year "Super Premium" price for a player who will likely be giving "Regular" performance in a couple of years (something I support, by the way). At the same time, they have not replaced them, in the short term, with players of anything near comparable proven (emphasis on proven) quality.
If Piolichick's track record is any indication, they have young talent on the Roster that will step up under the right coaching and as part of the right organization and assume the roles of several of these players. But, that's a development that will take a couple of years. Thus, I say that, for the Patriots, it looks like they have focused on "rebuilding" this offseason.
I think that this is the right strategy, by the way. We don't want to end up like the Steelers who took 26 years to win their next SB after a phenomenal run, or like the Cowboys who took 10 years to get back to being taken seriously for an SB or the '49ers who still aren't close after 11 seasons.
Look forward to your response.