Media bias is not the deciding factor between Republican victory or defeat. We can argue whether the MSM is worse today than it was in the Bush years or the Clinton years or the Reagan years. But few if any Republicans would argue that media coverage in any of those eras was good for the party. Yet despite the coverage of Sam Donaldson, Dan Rather, Peter Jennings, Bryant Gumbel, etc., Ronald Reagan won two landslides, the Republicans took over Congress in 1994, Republicans enjoyed good years in 2002 and 2004, and of course, we saw this November another example of widespread GOP victories while many are convinced the media is tilted against them. (Ask Rand Paul, Pat Toomey, Allen West, or Renee Ellmers how friendly the media was to them.)
Whatever filtering ability the media has, it is not capable of completely filtering out arguments in favor of electing Republican candidates.