There's really only one thing holding the Clan League back: some mechanism with which to compel clan leaders to use their entire roster.
So let's take it from the beginning. In the beginning, there was Exodus' Clan Wars, which was a 4v4 event. One of the problems with that event, that I and several others brought up at the time, was that there was nothing compelling clan leaders to use anyone except their top 4 players. So what I would like to do with my Clan League (which is essentially my version of Exodus' Clan Wars) is find a way to do that.
And I believe I have found a way. Or at least the general idea of way -- I still lack some of the details. The general idea, however, is that only clans and players who have participated in Clan Wars are eligible to participate in the Clan League. Moreover, when a leader uses a player in the League, he cannot use him again until ALL the players he has used in the Wars have been used.
So, with the Wars, the leader is compelled to use as many players as he can, because more players give him an advantage. But, at the same time, the more players he uses in the Wars, the fewer times he can use his best players in the League, forcing him to use everyone.
There are some details that need to be resolved. For example, what happens if a player is used in the Wars who does not want to participate in the League? Or who CAN'T participate, because he is busy? Or who simply quit playing PA in the meantime. Or who quit the clan. Etc.
But these are just details that I am sure I can work out eventually. The main thing is that I believe I have the general idea of how to force leaders to use their entire roster -- or at least as much as possible of it.
I will have more to say on the League soon, but for now this should provide enough food for thought for everyone. Let me know of your ideas on the subject.