The funny thing is there was an episode of The West Wing on this subject.
iirc Leo was running for Veep and had his buddies in the press put out a ton of stories about how bad he was at debates. When Leo proved to be adept he got a much bigger boost because he was perceived as the underdog.
But I don’t think that’s the case here. Vance isn’t ready to go toe to toe with a career politician who is getting help from people who worked with experts like Obama
“CBS has asked each candidate to fact check the other. In interest of saving time, I’ll just repeat all the times Mr. Vance and Mr. Trump have been caught lying. Let’s start with the Haitian dog BBQ’s and move backwards. Or would you prefer starting with Mr. Trump’s promise to have Mexico pay for the Wall and move forward?”