I've never completely understood it either. But recently I've come to notice some factors that may affect hubberscore:
1) Consistent activity; not necessarily frequent but regular. Consistently participate in the community.
2) Hub-hopping on a regular basis; choose a day of the week to hub-hop and rate some hubs.
3) Update your hubs regularly and often. Updating improves hubscore, and will help hubberscore, too.
4) Writing new hubs and letting them simmer before publishing immediately will improve your hubberscore.
5) There are more secrets but I will let you discover them as you keep writing and publishing more hubs. :)