i upgraded to all sum of fears 2 last month, but was at the end of the month on 3180 points and it deranked me to Sum of all fears 1 3000 points.
might be good to know that you have to be over the threshold to retain your rank and also points. arena still resting untouched on 2272.
this suprised me a little bit now being back in doomsday lol.
It will not delete your points on your uprise though.
You will also get the monthly reward pack of the higher rank, before you become degraded.