I would do this trade
http://www.espn.com/nba/tradeMachine?tradeId=y6cy84t8
To Kings: Smart, Theis, Nesmith, Waters, a protected 1st and 2nd
To Celtics: Barnes, Whiteside and 2 fillers
Barnes is a player Danny has had an eye on since HS. He has won a ring, plays good versatile D, good clean 3 point shot, doesn't need to launch shots, plays within himself. Probably the best complimentary piece you could find for Tatum/Brown/Walker championship pursuit
He is also signed up for the next 3 years.
New lineup
TT
Tatum
Barnes
Brown
Walker
Timelord/Whiteside
Gwilliams/Semi
Langford
Teague
Pritchard
With the luxury of having one of the starters on the court at all times
I like the idea of Barnes, but I would not give up Smart, and I don't think we would need to.
You do, because of salary matching purpose
Not enough min/underutilizing if you kept both also
Salary matching isn't the issue. We can absorb Barnes' 22.2M salary with the TPE.
The issue is making room under the tax threshold so that we don't end up paying the tax. To do this, we'd need to shed about 9M in salary. Maybe 12M to be safe in case Jaylen makes certain incentives.
We could send some of that to SAC in a side transaction or also could send some to a 3rd team in a separate transaction.
SAC would have an open roster slot with the movement of Barnes and could in theory cut GR III's unguaranteed contract so could receive two players without issue. You'd have to probably give them an additional future 2nd round pick for doing that.
There are multiple combinations of contracts Danny could move to shed that 9M-12M. I would assume at a minimum, he would be sending either Romeo (3.6M) or Aaron (3.4M) or both in such a deal. So to shed the rest will need to move 2 more players -- which means involving a 3rd team.
I get that since Theis is on his last year, that he is tradable, but this move is also about going all-in on this coming playoffs and I don't think Danny or Brad would want to replace what Theis brings to this team with Whiteside.
Javonte' contract is not yet guaranteed and in theory could be cut to shed 1.5M, but in a scenario where we traded away one or both of Romeo or Aaron, it would seem unlikely Danny would want to cut one more small wing / big guard.