I wouldn't label McClellan as a slugger only, he was (potentially) a great fighter who met a very sad ending in the fight game. He beat Jones in the Amateurs and in my opinion he would have beaten him in the pro ranks too. It would have been a closer call against Bernard Hopkins i think, but who knows what he may have achieved had he not suffered those injuries against Benn, and had he went about his work that night in another manner. He understimated Benn a great deal, even though the referee did Benn a few favours that night.
Manny Steward said that McClellan was potentially the most gifted fighter he had worked with and that speaks volumes.