If I'm answering this one in the fashion that some answered Broner/Mancini? Then, yes. Of course DeMarco can beat Mancini. Didn't you see how quickly he knocked out Molina?
Ray would tear this kid up in the typical aggressive and crowd pleasing style that made him one of boxing's biggest attractions of the early 80's. He would definitely catch some coming in and it would be a hell of a fight while it lasted, much resembling the Bobby Chacon donnybrook. Ray Mancini KO 4