Losing both Bill Russell and Sam Jones via retirement after the Celtics 1969 Championship was a real blow. Filling the hole at center was the main issue. Coach-at-the-time, Tom Heinsohn decided to go with three centers to fill the 48 minutes in the middle. Brad Stevens may have to take the same path.
With both Al Horford and Kyrie Irving almost surely heading elsewhere, it looks like Irving's slot will be filled with Kemba Walker, and his fit with the team seems like a good one.