I made this very request in the requests area. Right now its only looking at CPU utilization and doesn't know about the other factors with regard to CPU utilization.
I had some older hosts that while the CPU was only used at about 30% average, %RDY values were constantly 5-15 so it was becoming unacceptable and the only time DRS moved anything was when one or more of the VM's started going at 100% on my old dual socket one cores. New hardware solved that completely though (more cores) for me so its not an issue anymore for me.