Whichever team's melee scrum is larger and more skilled (or in a better position to over-take the enemy) is the team that wins 99.9% of the rounds.
Archers can be annoying, but I'm guessing people IRL didn't like being shot from a distance when they didn't have any ranged weapon themselves. That's something real armies dealt with, and something you can deal with as a player in c-rpg as well. Or you can keep running into them, and then QQ on the forums when you die.
Archers are pretty under-powered at the moment (as are horses maneuverability, and lighter horses ability to walk over more than 1 person), the problem lies with the battle game mode, not with archers or cavalry. Nobody is forced to fight over an area of the map. Nobody is forced to try and hold or take areas of the map (aka standing their ground). So archers and cavalry can kite and generally play less risky and still help their team win.
If we had a conquest battle mode, then infantry would be much more "powerful" on the battlefield, and really shine where they are supposed to, at taking and holding ground. So if archers want to sit on a hill when the enemy infantry is putting up the flag, the archers will lose (forcing the archers and cavalry to engage the infantry, rather than what we have now where infantry either camp or die trying to walk up a hill of 10+ archers).
If it's too much to ask to implement a "conquest" game mode, then have the Master of the Flag spawn 30 seconds into the map and let people fight over it (also make it randomly spawn around the map).
Also I agree that arrow stagger should be removed. It should interrupt your attack if you get hit, but you shouldn't be staggered for a full second +