I do think the team was constructed with Miami (and to a lesser extent OKC) in mind.
However, without Rondo, that whole plan is out the window. We aren't beating Miami in a 7 game series without Rondo. Nobody else on the team has the ability to step up and win 2 games in a playoff series by themselves anymore. That's what you need to beat the best teams. The Celtics used to have 3-4 guys who could do that. Without Rondo, they have none.
Even if they could beat Miami, I think they'd get beaten up inside over the course of a series by a healthy, young, big team like the Bulls. I wouldn't feel very good about their chances against the Knicks or Nets in a series, either.
I think an objective assessment of this team will arrive at the conclusion that it's headed for a first round exit, except maybe against Indiana, Milwaukee, or Atlanta -- but again, those are the weakest teams and yet they match up well with the Celtics.