The Mystery of HubPage Ranking
Like Google, the intricate algorithm for HubPages will not be revealed or discussed except in broad terms by those that started it and work in the back end of it. That said, earning money on Hubpages, Wizzley or Bukisa does happen, but don't quit your job, if you have one. I do believe it is a "numbers" game in some respects and until you have over 1000 hubs and hundreds of followers, your earnings are only double digit. Having a few hubs that have a 100 score is meaningless for the next week that same hub may be 89, because between the clicks on it and the search value of the words or topic is less. The HubPages ranking is just relative to how Google interacts with it and ranks it also.
Those with hundreds of followers and thousands of hub are, indeed, making three, maybe four (although, I doubt it) digit incomes per month. The more hubs, followers, and variety of topics you have, the more money is likely to come. If you only write about a certain topic most of the time, the appeal is limited to a small group. Being a good writer comes into play, also. Getting awards helps. All these things help (maybe) adjust your ratings in HubPages via their rating and algorithms internally and those of Google Adsense and its search engine using keywords and topics. Together, maybe your material is shown in searches more frequently than others without the ratings or followers.
Advertising using the Amazon or Ebay modules helps also. A reader might find your article interesting and then find a book or CD listed below and order it or click on it, which may give you a boost in income and\or rating.
Ratings of a writer fluctuate frequently. One week you are beaming at 97, and the next, 89. Why? Simply because one week the topics in your list were hot. People were searching for those topics (which is why to write about all things you are interested in) and clicked on them frequently. On the following week, for whatever reason, it was not happening, so the score drops. Nothing you can do about it.
Just keep on writing!