How does Pubsub Linkcount Work?

Pubsub linkcount is confusing. I have no idea what it means. One day bokardo gets 3 inlinks and its ranked 1,691 (in the top 4% of something). The next day it gets zero links and drops down to 91,755. The day after that its gets 6 inlinks and rises to 14,617. It would seem that the rank is based on the activity of other sites somehow. Is this just counting the number of links on a given day and ranking by that day only?

Does anybody know what this means?