At some point they added a feature that if your league battle points are full you can auto batle 15x if you got coins for days you can battle everyone in seconds and if you got some boosters you can beat SOME people higher than you. If they are not at like 900 or more than it probably means they lost some of those auto battles and since they done lost a match or more can be over taken at the last day or two by an active string player.