Support Case Backlog report

I'm not clear if the existing "reports" for Open Case Analysis are actually a backlog trend report or simply a case age report. Case age would just show me how many cases are currently open and when they were created. Backlog trend shows whether a backlog is growing or shrinking over time by showing what the backlog was at a given moment in time. My executives need to be able to see the backlog trend by product, source (email, web, phone, chat), time range, and period type. I don't see that I can put multiple filters into a portlet such that they can try various scenarios; the few attempts I've made with graphs only allow me to enter one filter.