I looked up the forum and found no subject about this :
I think there should be a system to limit player in a faction if another faction has almost no player.
Even if you have 10 extra good players in a faction, they may resist but they won't be able to resist a 100 medium player in an other faction, cause they will have only to defend from massive attack everywhere (and everytime).
So, what about a "balanced" number of player by faction ?
Hope it could help to improve the fun of that game