Why would the Nets do this?
They badly need a qualify PF to play next to Brook Lopez, the style of LaMarcus Aldridge complements Brook Lopez nicely since the former shoots a lot of mid-range jumpers while the latter tends to post up. I do not know how good Aldridge is at pick n roll, but hes young and can easily learn this with Deron. Deron also loves to play with a PF, Aldridge is an upgraded version of Boozer(though worse at rebounding maybe). The Nets do not have many trade assets besides Humphries expiring contract, but this one alone can make them a contender if used properly.
Why would the Trailblazers do this?
For the Trailblazers, it is about time to build around Damian Lillard, so establishing him as the team's clear #1 option is necessary. The 2014 NBA draft is gonna be really good, the Trailblazers can not only get additional draft picks from Nets, but also tank itself to Andrew Wiggins by trading Aldridge away. Humphries contract expires next season, which will be good for the Blazers. On the other hand, on a new team Marshon Brooks can improve beyond his rookie season's accomplishment if the coach gives him more chance, he can easily become a 16/3/3 player right next to Lillard.
Re: ESPN Trade Scenario: Brooklyn Nets and Portland Trailblazers
So the Blazers give up the best piece they have to put around Lillard to get raped by Humphries contract, recieve Marshonn "Kobe" Brooks (sucks), and some draft pick that probably won't be lottery? Nah. Portland gets voluntarily raped in this trade and makes Lillard less likely to stay. I just don't get it, Portland gets considerably worse, Nets get considerably better, and,.. yeah thats it