I always said the man could give a speech to an audience of two opposed factions, and each faction would believe he was on their side:
... during the campaign what Barack Obama offered the American people was classic epideictic in the Greek sense. A rhetoric that created a sense of collective community grounded in hope and a sense of reconciliation embodied in who he was as an individual and in that message.
That's been, that concept isn't new or controversial, I'm just going to assume that you'll accept it on its face. But the point I want to make about it is that the credibility of Barack Obama, an AfricanAmerican winning the primary in Iowa, giving this sort of message, meant that we were investing that message with Barack Obama. He became the evidence for his own message. And at a time in which the public was widely ready to repudiate George Bush, he became the incarnation of everyone's hopes and dreams as the "unBush."
As a result people read into his candidacy whatever they wanted, particularly everything they didn't like about George Bush. And every unfulfilled aspiration of liberals or progressives was also bodied in this person Barack Obama regardless of what he actually said.
In other words Barack Obama was never as eloquent as we thought he was. A person matched a moment with a rhetoric in a context in which the audience created something it heard as eloquence.
Via http://www.americanrhetoric.com/speeches/PDFFiles/Kathleen%20Hall%20Jamieson%20-%20Obama%20Rhetoric.pdf, itself via http://blogs.the-american-interest.com/wrm/2012/09/03/the-presidents-failure-and-his-challenge/.