A major clan had a big banner stack going, and it perpetually put the top-performing players that weren't in that clan on the same team as the banner stack, so they just kept winning.
Sounds like your problem is not being a top-performing player
Jokes aside, with lowering player count and increasing blocking skill, thus increased strength of ganks, a good team balancer is absolutely essential to the enjoyability of this game. Banner groups should weigh heavily, an equal division of classes should be taken into account, an unequal division of players should be a possiblity etc. Now, I have looked at the code and it looks like a seriously convoluted mess. Perhaps throwing it all away and starting from scratch might be a good idea? Perhaps the overlords can be persuaded to help out, or at least give some advice? Just saying, this shit is rather important.
