The only reason I see why Cleveland would do this trade is if they feel they need more speed in the front court. Tristan Thompson is too good to not play so Love can't slide down to the 5.
As for the C's, I can see how Melo can fit. At this point in his career, he's a 4 more than a 3, the same way Horford is a 5 more than a 4. He gives us an elite scoring option and he's a decent rebounder. And seeing his performances in team USA, I'm sure he can flourish in a team-based system. I firmly believe he's a high IQ player. The biggest downside is the defense, obviously. But if we could get him for Amir+Rozier+2018 BKN pick and salary filler, it sounds like a good deal.
Unless DA thinks we can be big players in FA (I assume acquiring Melo kills all our financial flexibility?)