I think the trade can happen, but we would need to add a 1st rounder to the deal.
How good we are depends on who we get. Milsap I think fits better. Jefferson is a great post player, but he would bog down our offense and significantly hurt our defense. As for Dieng, I'm not sure he's worth using our pick on. I would do Bradley, Bass, china 3 and a pick for Milsap though. Bradley's "talent' is waaaaaayyyyyy overated on these boards.
Bradley+Bass+China 3 + #16 .... for Millsap???
a) That's waaaaaaayyyyyy overating Millsap and
b) Is probably not really technically feasible given our current cap situation unless we do some _other_ major transaction first.
We are over the LT apron. We can't add salary except via exception (and even then only via minimum contract or the lesser MLE). A trade is not an exception.
We can only bring back less salary than we send out in trade. The above trade works for THAT rule provided Millsap signs for less than 12M ... BUT, it simultaneously creates several empty roster slots - each which will require a cap hold. So you have to get Millsap to come here for 12M
minus the cap holds for the resulting empty roster slots (which you will have to fill now with minimum players). So that means convincing Millsap to come here for ~8M or less.
Millsap just made 8.6M this last year in the last year of his contract. He's looking for a pay raise.