It is entirely variable based on the number of factions that participate and while points matter it does not explicitly determine which Division you will end up in. Given there are 5 divisions the top 20% (based on points) go to Div A, the next 20% to Div B and so on down to Div E. So lets say your Faction was in Div B last event but you were right on the cusp of qualifying for Div A, if your faction got stronger by the next event OR some of the Div A factions from last event do not sign up for the next one your faction would probably make the jump from Div B to Div A. Does that answer your question? Let me know if that is not clear.
