If Doc loves smallball so much, Danny Ainge should try to give Doc bigs who fit into that style. Or fire Doc, but I don't think that is happening, nor do I want it to happen.
I think DJ White and Shavlik Randolph have skill-sets that could function in that role, so I'd like to see them get time for a proper audition in that role.
Looking towards next season, one name stands out to me. I'm not sure if the Celtics will even have the full MLE available and I think he can get more than the MLE, especially from his current team, but the ideal guy would be Elton Brand, a defender/enforcer who has experience as a smallball PF/C.
Carl Landry is another player with smallball experience. He has a player option and is probably interested in declining it if he can get a long-term deal somewhere, though it sounds like Golden State would be his first choice.
If Doc Rivers wants a big who is intelligent enough to understand the defense, capable of defending a stretch four out to the perimeter, and preferably able to stretch the floor a little by being able to score occasionally away from the basket, who's available? If you're thinking trade, a pupu platter of Jason Terry, Fab Melo, and an un-guaranteed Chinese All-Star will allow you to bring back someone making about $9.3m. Jordan Crawford and 2/3 of the China Three would allow you to take back around $5m.