I highly doubt that the Cs are interested in Drummond.
The other day, Ainge was pretty explicit in a Bulpett article about bigs that the team wants:
on the subject of big people, Ainge has said he doesn’t want anyone who would hinder the Celts from playing their preferred offense in which the floor is spread.
Doesn't sound like Drummond to me. I think that Stevens and consequently Ainge give lip service to rebounding as there is so much criticism on our lack of it that they almost have to. Spreading the floor is more of a priority for them.
Also, Drummond will not come cheap. Can't kill our flexibility for such a one dimensional player that you ahudder to put in at the end of games because of his FT shooting.