By making it 720 you have just made everyone keep their ranks from prior to 6.2 and for everyone else unachievable....AGAIN
I lost rank of 5* three times due to having suffer a change from Abyss to HP system, then 2 merges. and the 2nd time I have been gaining levels back, but the gap between my level and 5* doubled.
yes it's unfortunate the losing faction that they are losing the ranks. But this meant that all different people would have the opportunity to rank. If you are going to do this 720 then just wipe the HP Ranks from everyone.
6.2 pretty much reset the game, so Reset the HP rank to 0, because if my faction wins every siege then the ranks just go back to what they were before and without anyone having any chance in the world to increase their levels.
LEAVE IT AT 900 or RESET HP to 0!!!!
As soon as you skip one, that's it, you are off the ranks