Hi Joe,
Welcome back!
Ranks are tied to mobs. There are hundreds of "rankmobs" throughout the mud. Some are much more obvious than others. The more often a mob is killed the lower % you will earn for killing it. So there is a passive bonus gained from exploration rather than running laps around the mud killing the same mobs over and over again. Also, ranks can start accumulating at lower levels now, as you found out.
I hope this helped!