I have been watching and researching Hubzu for many months and what I found is that Hubzu has a sophisticated calculation to determine reserve and opening bid based on prior bids, BPO as well as a WAG.
Also each property has a local agent/broker associated with it and it looks like the agent/broker can over-ride any number presented by Hubzu.
What I do is determine a fair price (ARV) for the property. Then the price I am willing to pay will determine what I do with the property (Flip, Hold for Rental or no bid).
Bottom line is you have to feel the price you pay is in line with your plans for the property and then bid.
There are good deals to be had on Hubzu, but if it were easy, everyone would be doing it.
Don't try to figure out Hubzu, because IMHO, I don't think anyone will be able to understand the full logic of Hubzu.
My only suggestion is to have a plan and bid based on your plans and goals and keep emotion out of it. This is a business and should be managed like a business.
Good luck!