There's no excitement = low turnout = Dem support drops
This. VA-10 was going to be the only competitive House race, and even that's not really competitive now. Comstock should win comfortably.
There's really no excitement (or reason to be excited, really). The 2013 race was so horrible. Between that and the recent, not-so-great developments in Virginia politics (McDonnell trial, etc), I get the sense that people are simply fatigued and demoralized.