Even taking into account the normal exaggeration of the build-up to a high-profile contest, McClellan's was a chilling presence in London last week. "You can't make a puncher," he said. "It's something that's in you, something I find tremendously thrilling.
"I get a greater buzz from a knock-out than I do from sex. Getting the power on, watching an opponent fall. There isn't another experience to compare with it."
At 27, with a truly spectacular record behind him, McClellan had the devastatingly explosive quality television demands of boxers in return for the huge riches it can bestow, and he was clearly pursuing a bright future.
The American had 29 knock-outs to his name, and 20 of those had come in whirlwind first rounds.
He seemed simply to be getting better - his last three defences of the middleweight title lasted a total of 210 seconds. Jeff Bell was disposed of in 30 seconds (the fastest middleweight world championship in history), Gilbert Baptiste managed 97 seconds and Julian Jackson 83. Only three of his last 21 opponents had lasted more than three rounds.
The Jackson fight was his last at middleweight as he was, literally, growing out of the division. He shed 10lbs on the day of the weigh-in for his fight with Jackson in May and moved up to the 12st division for his meeting with Benn.
When he arrived in London to build up the fight, his confident articulation of menace swiftly became the week's dominant theme.
"Knocking fighters out gives me the greatest buzz. It's a great feeling to me, knocking men unconscious and watching them fall.
"I'm always looking for a first-round knockout; it's the goal I am aiming for in this one," he said. He spoke quietly about his ferocity in the ring being as instinctive as that of the pitbull terriers he bred.
But, fearsome though his boxing was, the man from the small town of Freeport, Illinois, had not yet broken through in terms of world recognition.
"He is not a household name in the States," the respected American boxing writer, Ed Schuyler, said. "He is not one of those fighters who is known beyond the game. He kept a very low profile between fights - he would fight and then disappear until the next one.
"He has always been thought of as a bit of a loose cannon. He is his own man, and likes things done his way."
America had also still to be convinced as to his real stature in the game, Schuyler said.
"He doesn't train very well, and he tries to win every fight inside one round," he said.
The fact that he could not gives an added thrust to his words last week.
"I really think I'm destined to be the future of the most exciting division in boxing, where you get speed and power and the best punchers of all."