In the draft they added Jared Sullinger and Fab Melo, who could be the future frontcourt for years to come. Through free agency they replaced Allen with Courtney Lee and former sixth man of the year Jason Terry.
Putting the additions alongside Kevin Garnett, Paul Pierce and Rajon Rondo, this looks like a team ready to make another run at the championship.
With the roster nearly set, it comes down to adding some minimum-salary players to help fill out the bench. They are in need of another guard as well as another big man down low, and you can never have too many shooters.
Here are some of the best from the summer leagues that maybe the Celtics should keep their eyes on.