Charlie wasn't going to hurt Logan anymore than he needed to, but he wasn't going to take the blows. He defended himself; he worked to get the frat boy pinned, to get him to come to. He wanted Logan to recognize who he was taking swings at.
Charlie knew how to hold a man in more than one way. Some ways were more painful than others; some weren't even allowed by the police because they were much to harsh, considered abuse.