The rationale for switching is that Bernie did better across the country while Hilary won her lead in the South which should already be conceded to Trump. Undemocratic? Yes. But Bernie polls better against Trump. Probably due to that lack of charisma you mentioned. Either way Trump's gonna get pummeled by the right's longest serving boogeyman or a socialist so I don't know that the superdelegates are gonna follow my rationale.