At the risk of getting flayed by the merciless Celticblog forum.
http://www.espn.com/nba/tradeMachine?tradeId=zvygc2b Boston gets: Cousins, Bogdonavic
Nets get: Gay, Johnson, rights to swap pick with Celtics in 2017
Kings get: Lopez, Bradley, Brk 2018 pick
Boston gets Cousins while only giving up Johnson, Bradley, and the Brk picks. They keep Smart, Brown, Rozier, and Olynyk to go with the core of Crowder, Cousins, Horford, and Thomas. This team can compete this year and the next few years against the Cavs. Obviously Cousins fits a huge need as a scoring option at PF, and he fits perfectly next to Horford. I really like Bogdan too. I think in Stevens' offense, Bogdon could be our starting shooting guard, or our 6th man scoring punch.
The Kings don't want a complete rebuild. They want to compete. Lopez and Bradley are two fringe all-stars who fit into Joeger's defense-first, grinding-offense style. This gives them value for Gay and finally fills their shooting guard hole, while also filling 75% of Cousins scoring. At the same time, they get a 2018 Nets pick that is probably a lottery pick to help their rebuild. Their core going forward is Bradley-Lopez-WCS, with replaceable veterans. I think they would be just as competitive with Bradley and Lopez as they are with Cousins and Gay, but this resolves the Cousins situation, gets value for Gay, and gives them a future lottery pick.
The Nets have Lopez on minute restriction, and it seems like they have been testing the water to trade him for a while, Gay and Johnson are both veteran players on expiring contracts that allow them to compete this year while giving them flexibility into next off-season. The prize of this trade is that they get their 2017 pick swap back, which jumpstarts their rebuild in a deep class. Their roster is still bereft of talent, but this gives them more opportunities to get talent.
edit: I answer this later in the thread, but if you are wondering why we give up a 2017 Nets pick for Lopez, the answer is that in this 3 team trade, we aren't giving it up for Lopez; we are giving it up for Cousins ultimately.