Now Biden, who has been to foreign policy in the Senate what Ted Kennedy has been to domestic policy (almost anyway!)...Wait. Ted Kennedy was a stalwart supporter of liberalism for his whole career. When it was cool, when it wasn't, he was there, getting stuff done, making progress.
Joe Biden is not that. He is a prominent liberal hawk who enthusiastically backed Bush's war, and then tried to escape from it by criticizing the execution of the war. Admittedly, in the past year, he's made some impressive strides and doesn't even seem to much support the Iraq War anymore, although he's a tick or two to the right of, say, Barack Obama. I've actually kinda come to like Biden, truth be told, but he isn't exactly synonymous with keeping the faith. In terms of sheer knowledge, perhaps the comparison is more appropriate, but it's kind of a stretch.
Of course, considering that most media types supported the war, perhaps Biden is seen as a keeper of the faith, as his evolution has been similar to the conventional wisdom of Washington at every step of the way.