From a pure player value standpoint, Brogdon + Gallo for Porzingis is about fair. You don't know what you are going to get from Gallo but probably 8th or 9th guy off the bench. Brogdon is the 6th man (albeit a starter on many teams). Porzingis is an all star level starting PF/C. All 3 players have injury questions/histories. I could see Porzingis picking up his option to play for the Celtics, not sure Gallo does to play for WAS, but maybe.
The problem I have with this is why would WAS do it. They are already down a PF by trading Hachimura. They may lose Kuzma. Brogdon and Beal would give them a very solid "win now" back court. Then they have Kuzma and a bunch of unproven young players. Don't see that team going anywhere really. I guess if Porzingis says trade me or I walk, then maybe something like this. Porzingis would be leaving a lot of money on the table likely, if he were to walk and test FA.
Washington would do it to enter rebuilding which they should do. Pick up a 1st, Gallo's expiring, and then rehab Brogdon to move later on for additional assets. Then they trade Beal for the real haul and fully rebuild. It might take another asset or two, but it at least in theory makes sense as a rebuilding type trade and I'm not sure they'd do better than that for the Zinger given he is expiring and hurt a lot.
Zinger, Morris, 42
For
Brogdon, Gallo, Pritchard, Kornet, Muscala, 24 1st, 26 1st (lotto), cash
Something like that, I think makes sense for both teams.
C's post trade
Starters - Smart, Brown, Tatum, Zinger, Rob
Rotation - Morris, White, Hauser, Grant, Horford
Bench - Davison, Champagnie, 35, 42
1 open spot
That seems like a better and more balanced team. Does eliminate some future flexibility, but I do think thst team is better and that should be the goal.