Sorry I didn't read all of the thread, but this is my opinion on the matter...

-Melee teams are best in close combat like inside of buildings and towers and killing while moving.
-Ranged are best out in the open or places where you can remain stationary while constanly nuking the crap out of the opponents.

Of course that doesn't mean that either team couldn't do well in either enviroment, just that imo that is where they do their best at.