A lot is going to depend on how the Celtics do in the playoffs, but are the Celtics destined to be one of those teams who have a great collection of players who can never break through?
Other examples: mid to late 00's Wizards: Arenas, Butler, Jamison all playing at all star levels, yet I don't think they ever made it out of the 1st round. Good role players, too - Haywood, Daniels, Songaila.
mid to late 00's Nuggets: Iverson, Billups, Anthony, KMart, Nene, Smith, Birdman. An excellent combo of defense and offense (on paper). Sort of amazing they never made a finals.
Early 90's Sonics. Had Kemp and Payton, had a 63 win season where they lost to the Nuggets in the 1st round.
There are teams like the 01-02 Kings, who got cheated by the refs and the 04-05 pacers, who had a good chance to win it if it wasn't for suspensions, that I won't count.