A slick, hard-hitting technician in the ring, McCallum was known for his exceptionally durable chin and toughness, and was never stopped in any of his five losses. He earned his nickname of "The Bodysnatcher" due to his ability to land vicious body punches in fights. McCallum was inducted into the International Boxing Hall of Fame in 2003. In 2011, "The Ring" magazine ranked him as eighth on their list of the "10 best middleweight title holders of the last 50 years."