Why are Republicans promoting the idea that McCain's a maverick?

In saying we should vote for him because he is an agent of change, aren't they saying that their own party has done a horrible job over the last eight years? I mean, I just don't understand how they can say, "vote for McCain, he's a maverick and will shake up Washington" and "our party did a great job running the country over the last eight years so we deserve another four" at the same time. McCain/Palin is not convincing.