He makes his opponents to work hard while he is backing up and rarely contr - punching. After opponent is tired to hell, he takes advantages. This is not the engage and war that Kovalev likes.
Hopkins style reminds me of Jack Johnson's, funnily enough. It's not just slapping an old school label on a couple of moves for the sake of sounding trendy, but watching him fight, it'd fit in damn well in the rugged days of 1914 as well as it does in 2014. It's a perfect case study that modern fighters, although they may be refined in certain areas and look cleaner on tape, may not be as well equipped to deal with the rough-housing, spoiling tactics that old timers had to deal with on a more routine basis.