This is how I personally would change the allinace championships to be hard but achievable and so that it isnt easily exploited by alt accounts. I know this cannot be implemented right away but mayby for next one.
Considering that I think an decent average to consider for rank 10 rewards are 1250 points from every member. If this is achieved than it means that particular alliance has reached 300000 points total.
And as alliance ranking should not only be calculated by tournaments I would also implement the alliance missions.
To give this one 300000 points total too would mean every rank up is worth 3750 points.
So make rank 10 rewards like this 600000 Which is hard but still possible.
This is just my suggestion. If anyone has other suggestions just post them below in this topic to have all change suggestions at one place so they can easily find them all.