HubScore, on a number of levels is a measurement of trust and quality between an author of a Hub, and how people interact.
While I won't go into great details, your author HubScore and your Hub HubScore flow in both directions. Here is a simple example. Let's say I become your fan, since I have many fans with high HubScores, that's going to flow to your author HubScore. Now, let's say you publish a new Hub, that new Hub will inherit some of your author HubScore, and as we learn more about the Hub, the score of that Hub will flow to your author HubScore.
The important thing to know is HubScore flows in both directions.