I don’t know that I’d be too worried about that Bayard. She’s decent with the canned speeches and okay with using policy sound bites to dodge questions, but it’s clear she’s prone to collapse anytime there’s no script. She’s lost the image as the “ringer” for McCain, and the image as a highly intelligent, attractive, ideal female VP candidate. While she’s still a favorite of the rabid right, I can’t help but wonder if they aren’t wavering a little, simply because it’s clear McCain’s people are telling her what to think. How influential is she going to be when he’s in office and pushing policy away from what that rabid right want? There’s already been talk of her going away, stepping down, resigning, even getting fired.
And despite her being the VP candidate, this leaves a massive hole for Dems to exploit, either directly or through proxies of various sorts. She isn’t thinking for herself, she’s a puppet, she’s too chicken to even risk an interview, etc. For having a month left in the campaign, there’s a lot of subtle damage done, and in a sense, her being attractive may start to work against her if she can’t show some presidential ability or intelligence during the last few weeks. “Ditz” is already being tossed around, and she’s got that cruel impression she’s got to shake, as well. SNL is probably going to haunt her dreams till she dies, too. If she wins and I was Tina Fey, I’d probably flee the country. 
It wasn’t Biden’s best showing, but long-term it wasn’t bad. Attacking her might have won some points with the home team, but letting her fail on her own was probably the better strategy for the long term.
Philo, the source doesn’t really matter here, impression does. CNN has plenty of viewers, regular and sporadic, and often all it takes is pointing things out. For hardcore party members, such things are laughable. For the other 60% of voters that are straddling the middle or only leaning a certain way, those little details make a big difference, no matter the source.