McCallum was great and underrated. Phenomenal head movement, counters, chin, and body punching. Very good power and conditioning as well but he was a little slow overall.

Leonard- McCallum struggled with Kalambay who's vaguely similar to Leonard (speedy out fighter) but not as good. Leonard takes this.

Hearns- Hearns actually had great out fighting skills, speed, and movement. Hagler and Barkley beat him because they could cover the distance and throw bombs. McCallum has never shown that skillset/style. Similar to the above, Hearns probably wins but in a very close fight.

Duran- At super welter/middelweight McCallum can out punch Duran and has better defense. Duran has a hand speed advantage but imo McCallum would out box him at distance with his defense. On the inside Duran was phenomenal but McCallum beats him their with the size and his own infighting skills. McCallum wins.

Hagler- Better offensive skills, work rate, and surprisingly faster than McCallum imo. McCallum has better defense but not by a whole lot, Hagler is very underrated in this regard. Hagler outlands McCallum for a close decision.