There are times of day when the only bases u will see only show 0-1 or 40 crowns. We haven't figured out why. But usually if you fight one of these low crown ones or go off for awhile it will go back to normal.
It isn't just crown levels that determine match ups. It can't be. You see level 30's in rotation that surely don't have 2000+crowns. It would be nice to know, but I don't think they will give us exact criteria.