No game is perfect, nor will one ever be. I remember first person shooters like Quake, Half-Life, and even the Team Fortress Classic or Counterstrike MODS. Everyone online complained about getting sniped. I relate that to getting cherry-picked in the main arena. It sucks, it really pisses you off to no end. But ask yourself, does it make you mad because the other guy is exploiting a weakness in the game or the fact that you were not have been paying attention to all the areas around you at that time and he got you at a weak moment? The DA and CT (to some extent) have the 1 vs. 1 thing at co-alt going on more than the MA.
If you notice that guy above you, let him commit, then before he gets TOO close, roll and pull him down to the deck right into a gang of your countrymen, that usually makes them go away pretty quick. If he doesn't follow, just keep moving on, most likely he will as well. Alt is a big advantage, he's exploiting that, so take his away as well. All you can do is play the game the way you'd like it played, and learn how to deal with the others when you are in the air.
--Howitzer