Mavs can trade AD for a rebuild, or trade #1/Cooper for a win-now group. This is winning now, simple enough.

Celtics trade all three of the big 'support' player contracts, replace them with three good-enough players on expiring contracts. It saves $32mil now (plus over $100mil in taxes), then lets them decide their path next year based on the results ... while free from the 2nd-apron rules. Note they keep Horford and Kornet under the 2nd apron.

Pelicans sacrifice their best 'support' players for the #1, and they have the picks to bring in more young talent with Cooper Flagg (starting with #7). They bring in a solid group of "good old dudes" who have helped some of the current stars win their rings. They can teach Cooper and the kids how to get there ... while growing old and eventually retiring. They don't need to go anywhere.

Finally, sorry for all those roster moves. It would not allow the trade to work with free agent holds.