Well i don't think all have the same timezone to play, so what if the other guild got more players in a same timezone and the other team with low players? that's a simple lose. xD
About the timezone, if i remember correctly, "Crew Wars" started at 8 P.M. (GMT+1 Dublin, Lisbon, London). About the weaker guilds, they used to create alliances with other guilds and it was fair imo. Imagine a guild with 20 "strong" members vs a 3-guild alliance with 60 "weaker" members.