Rocky Marciano had more stamina.
Watch his first fight with Ezard Charles [who was a great boxer-punches].
I have never seen Ali finish a 15 round fight in that passe. Marciano was throwing punches like it was the 2nd round. Ali-Frazier 1 was in a similar passe, and both Ali & Frazier were hardly throwing punches.
George Chuvalo is a puncher, not a swarmer. Chuvalo never had a 15 round in the pace of Marciano-Charles. Marciano made his Charles fight a high pace fight, just how Frazier made Ali and Chuvalo fight in a fast pace. Chuvalo could not handle a high pace fight, Ali could hardly handle it [watch Frazier-Ali 1].
I would have to give the slight nod to Rocky Marciano in terms of stamina. The reason for this is because, while Muhammad ALI could dance for 15 rounds, something no one else could do, he had some degree of control over how much stamina or energy he exerted.
ALI had the uncanny ability to stay just out of range and keep an opponent from hitting him. Then he'd dart in and tag at will. However, again because the opponent could scarcely reach him, he had some degree of control over how many punches he wanted to throw, thus how much energy he exerted.
In the case of Marciano, he had no choice but to go after his opponent and take whatever the opponent dished out. He threw his punches but in many cases, over half of them missed. Missed punches take more than twice the stamina of landed punches because of the kinetic energy that travels from body to body.
Marciano would land enough punches to wear his opponent down but he would miss over half in the process. The bottom line is that he got the job done.......49 times....... and retired undefeated.
The undefeated record doesn't solely prove his greatness and it could be argued that he went largely untested. However, your question is one of Stamina and I believe Marciano gets the nod here.
In boxing I consider stamina to be throwing bunches of punches every round, not dancing around avoiding throwing punches except toward the end of the round to score a few points.
Marciano was a punching machine, he took as well as he gave and he did not run and hide.
I think a prime Muhammad Ali had better stamina. Rocky is noted for his stamina but the Ali of the 1960s could dance around the ring, throw wicked combinations and fight at a very fast pace even in the last round.
Thoughts?
