There aren't any 7 foot centers on the Celtics Summer League roster with the exception of Iverson.  And he seems to play more like a 4.  Every summer the Celtics always bring in 1-2 seven footers.  They never have enough talent to stick.  So, Danny and his staff aren't inviting any this summer. 

http://basketball.realgm.com/nba/teams/Boston-Celtics/2/Rosters/Summer_League

Even though there is a glaring need for a defensive stopper what is the fallback plan for acquiring a 2nd or 3rd string center for the upcoming season?  There doesn't appear to be any plan...this was alluded to in another post. 

Recent history suggests Brad will play Sullinger at center when the need arises.  Doc used Glen Davis in a similar role.  Brad could play Anthony, who is a much better defender.  Yet, his offensive skills keeps him perpetually in the coach’s doghouse.   

Last year it was frustrating watching talented 7 footers drop 4-5 consecutive shots over Sullinger before Stevens realized he couldn't guard them. Eventually, he would take him out of the game.  Unfortunately, the damage had already be done. This strategy reminds me a lot of Rick Pitino’s full court press defense from the late 90’s.  How many seasons did it take for him to realize that it didn't work?  How pathetic!!! Hopefully, Brad and Danny will find a better defensive scheme than having Sullinger play center against much taller aggressive scorers. 
 
My feeling is Danny may reach out and sign another non-athletic, good-shooting Euro to fill out the roster.  Or, he may sign Iverson and Brad will play him as much as he does Anthony.  Thus, another wasted space on the roster.  To me there is too much talk about acquiring more guards or mid-level talented 3’s and 4’s. What is the answer?  I can’t say.  I just know we can’t rely on Sullinger to play center on a regular basis.