So in that trade
Boston would be
Starters - White, Moody, Brown, Porzingis, Kessler
Rotation - Okoro, Pritchard, Hauser, Scheirman, Tillman
Deep Bench - Walsh, Davison
IR - Tatum
It would make sense to shed more salary and there are now more options and easier for that to get done with the more moderate salaries. That also makes it easier to build a better contender in 27 without doing much else as Kessler can slot into the Zinger salary slot when he leaves the team.
Cleveland would then be
Starters - Holiday, Mitchell, Hunter, Collins, Mobley
Rotation - Podz, Wade, Strus, Tyson
Deep Bench - 21, 28, 32
So a bit better balance and fits, though obviously they do lose the more talented players. It is a salary reduction for them as well. I think they do something like that if they really like Podz going forward and want to try to win and build for the future with the younger players. So Holiday provides them a bigger defensive guard than Garland, Mobley gets the paint all to himself as Collins can play out to the 3 line and keep the middle open, and they try to win the wide open east next year.
Golden State would then be Curry, Hield, Butler, Green, Allen with not much else though the ability to re-sign Kuminga. They do this trade to capitalize on the next season or two of Curry and Butler before they age themselves out of contention. Allen will still have value so they can trade him and reset when age becomes an issue but in the short term, he provides them the big body they need to better compete out west with Jokic, Davis, Wemby, Chet, etc.
Utah gets the scoring guard that Ainge loves and who played well with Lauri in Cleveland. They can also move Sexton or just keep him as 6th man type player, especially with Garland's injury to start the year (so they can also likely still tank since Ainge apparently loves doing that as well).