Why is it not a good system?
Some guilds will only join guild battle at the end of the week to get a good position. And why is that?? Because every guild starts the week with a rating at 1000 points if you lose battles during the week you will lose a lot of points, soooo the reasonable thing to do is wait till the end of the week to join to be ahead of the other guilds that are fighting each other.
Why dont you make a simple Guild Battle System that makes guilds want to fight each other for points?
A very simple one would be, if u lose a battle you earn 5 points if you win you earn 15 points, so guilds that are fighting for points wont have to worry about this terrible system, this simple system would make guilds want to fight each other to accumulate points, I have not come to think about a better one , but the one we have right now is terrible.