Moving alliances

I notice again how some alliances that were at the top of the League move to the League above after the start of the war. How it happens ?

I think that happens if a team in the higher league doesn’t have enough players to go to war. They get dropped down to league of mortals and another team gets promoted. 

This happens in all leagues. But the League of titans and gods.

That’s not true. It’s happened in both of those leagues. 

I’ve seen all the leagues. Movements were in all leagues. Only the League of titans remained unchanged. As for the League of gods, I’m not sure.

League of Gods had an alliance drop out after last war. League of titans has very stable alliances, so it’s unlikely that an alliance there would get down to 7 players at the start of war but it happened once in week 1.