It's (broadly speaking) conservative in the morning, DC "center right" CW all day, and then liberal in the evenings. I'm sure they imagine that the daytime is 'straight news' or whatever but it also has a perspective, and one that isn't that appealing to liberals. Andrea Mitchell ain't liberal.
I have no idea if having a more consistent perspective throughout the day would help ratings, but it just isn't the case that there's a TV home for liberal news junkies.
