Draft position:
Kevin McHale: 3rd (1980)
Larry Bird: 6th (1978)
Robert Parish: 8th (1976)
Kevin Garnett: 5th (1995)
Ray Allen: 5th (1996)
Paul Pierce: 10th (1998)
Rajon Rondo: 21st (2006)
Kendrick Perkins: 27th (2003)
J.R. Giddens: 30th (2008)
Bill Walker: 47th (2008)
I'm not saying it's not possible, but...
The Boston Celtics were the first NBA title team to not have a Top 3 draft pick on their roster since the 1983 Sixers, whose highest pick was Bobby Jones at 5. Of course, if not for the ABA, Moses Malone and Dr. J would probably have been Top 3 picks.
it's unlikely that the Cs will have three great players develop out of this group, but you never know. I can see Rondo being an all star PG in a couple of years. The two rookie swingmen have a long road, but both have tons of talent.