Let me just first say that no matter how bad DA wants to move up to land a high pick in this draft it still may not happen. Teams get locked in on prospects and feel they need to feed their fan bases in the moment with youth and potential. There is no better example then the year DA almost traded the farm for Justice Winslow but no one would take it.
This post is based of the rumors that the Cs are high on Bamba and Doncic and have explored moving up in the draft.
I am assuming that at the very minimum a trade up into the 4-7 range would cost the Cs Rozier, #27, 19 Sac pick, and an additional 2019 1st. With that additional pick likely being the Grizz pick.
Pros,
The Cs have their established core. Irving, Tatum, Brown, Hayward and Horford as the starts for the foreseeable future. If all works out they will retain Smart and Baynes cementing in their top 7 next season and will fill out the rotation with a vet min, Semi and Theis. Keeping this group together will leave little room to add multiple rookies in 2019
It seems very unlikely that Anthony Davis, the only player I would want to see the Cs make a push for trading is going to hit the open market. His ability to sign a super max and their recent playoff performance has me skeptical we will leave in the next few years. Aside from Davis or maybe KAT its hard to find a trade target who is a big enough roster upgrade to warrant using the cash of picks.
The 2018 draft is deep in big man depth while 2019 appears shallow. If the Cs want to land a high ceiling player to play behind/along side and learn from Horford this might be the Cs best chance. Adding and developing a young big now would start the Cs prep for the post Horford prime years without having to shake up the roster. As a team who is not going to see cap space for a long long time this maybe critical.
This class includes 5 potential all-star level centers in Ayton, Jackson, Bagely, Bamba, and Carter. All 5 could conceivably develop into modern offensive centers. Carter and Ayton are the most refined, Jackson and Bagley showed some perimeter skills in college, and Bamba is remuored to be a better perimeter shooter then he showed in college. On D Jackson, and Bamba could be elite and Carter really good. Ayton and Bagely have the tools to be good but will require work.
Adding an elite center prospect now would allow the Cs to let Baynes go if his contract demands are to high. Then sign a cheaper stop gap big to a one year deal or trust Theis and the Rookie to fill Baynes role.
Cons,
The Cs tried to go down this road before and rumor has it that trading away a bunch of picks for 1 pick almost cost the Cs the picks that became Tatum and Brown.
The Sac pick could be a top 5 pick next year and at that point a player like Reddish, Zion, Bol or someone else could be a better prospect then the player the Cs trade up for this year.
As good as the 5 bigs I listed are or can be all 5 have blemishes as prospects. Ayton lacks desire and awareness on D, Bagely is one hand dominate, lacks ideal length, and has questionable awareness on D, Bamba needs to get stronger and prove he has an offensive game, Jackson is still raw in a lot of facets of the game and will need time, and Carter as the most well polished and NBA ready lacks the ceiling of the other 4.
Giving up all those picks can be scaring the the quick changing nature of the NBA. For all we know Giannis, Davis, KAT or another "star" might get upset early next season and demand a trade at the deadline. The Cs are right now prime to jump on any such occurrence.
Conclusion
With all that being said I say go for it. Ainge has constructed an amazing roster and the potential to add a high end big man is to good to pass on. The question is who makes the trade.
Memphis #4 has been mentioned but they have no need for Rozier and including Brown is a horrible idea
Atlanta #3 seems too high to get to but maybe they look to create a 3 way where they trade down with another team. Something like Bulls #7, Portis and a future pick from the for #3 (allowing bulls to get Porter). Then they trade away Schroeder for ? (maybe to Pacers for #23 and something else) and make a #7 for Rozier and Sac pick (as long as a center is available)
Magic #6 this makes the most sense Rozier, #27 and the Sac pick is a nice haul for the #6. The magic are likely going to have to clean out their roster and go into a longer rebuild/reload. They have Issac as a potential future piece and Gordon as a RFA. Bringing in Rozier and retaining Gordon while looking to move Vuc and Fournier for youth/pics could be a good start. They would then likely be right back into the lottery next year with their pick and the Kings. At that point they could figure out their Issac and Gordon fit and hopefully add two starters to their team.