The Antagonist's performance is something largely dependent on the player's skill. It's easy to get discouraged by early games where an experienced Raiders Team can pile up and totally neutralize an Antagonist.
However, once you get a good understanding of the map you are playing in, and the team of Raiders you are facing, you can come with different strategies in order to be successful. A good example is precisely what alef321 comments -they clearly faced an Antagonist who knew his business.
But it works the other way around too, as you can make sure no character is left unprotected and susceptible to being ambushed.
Please, remember the melee system works on both ways! For every move, there is a counter. Whatever the Antagonist throws at you, you can beat.
Thanks for the great feedback guys.