If we're going to trade Pierce, then I think this would benefit the C's the most.
Boston sends: Paul Pierece & Fab Melo
Boston gets: Demarcus Cousins, John Salmons, Aaron Brooks
Memphis sends: Rudy Gay
Memphis gets: Paul Pierce
Sacramento sends: Demarcus Cousins, John Salmons, Aaron Brooks
Sacramento gets: Rudy Gay & Fab Melo
Why for Boston?
DMC is the big that they need now and for the future. A future core of Rondo, Bradley, DMC, Sully & Green is a pretty good core. In the meantime, you have a starting core of Rondo, Brardley, Green, KG & DMC. Salmons can back up Green at the 3, Brooks gives the C's a capable backup at the point. This type of trade would probably allow Ainge to move Terry and or Bass for some other pieces if needed.
Why for Memphis?
They apparently want to get under the luxury tax limit and while Pierce doesn't help with that this year, he's only guaranteed $4 million for next year. However, he probably helps them more this year in the playoffs than does Gay. In fact, there was a lot of talk down in Memphis that the team played better in last years playoffs without Gay then with him.
Why for Sacramento?
This only works for them if they are truly done with the headache that is DMC. If that is the case, then with this trade they add an athletic and high scoring SF that they lack, as well as a young center with some potential. They can keep Jason Thompson at the 5 and this would free up some more time for their top 5 pick Robinson.