Michael Spinks was way superior to Leon in every way. He is a top 5 light heavyweight champ of all time. He also became a heavyweight champ for a few years. He was not a top heavyweight but was better than Leon. Leon was a one fight wonder defeating an unmotivated undertrained out of shape Muhammad Ali. Ali easily defeated Leon the second time around. Leon was consumed by drugs and did not have any discipline. Michael was way better all the way around. Michael by a lopsided easy 15 round decision.
Both brothers were too small for the heavyweights and could have been better off sliding back and fighting at cruiser weights which Leon actually did with initial success. But even there, Leon was no longer up to the task having been ravaged beyond repair physically and emotionally at the heavyweights by Ali, Holmes and Coetzee.
Prime for prime, though I pick the Leon Spinks of the Muhammad Ali 1 vintage to spank his baby bro, Michael.
I really never like even the idea of brothers fighting each other but lets have some fun anyway.
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This might sound crazy, considering the comparative accomplishments of each, but I think Leon would beat Michael.
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Think about it for a minute. Michael was able to keep all of his opponents at bay (um except Mike Tyson). But look at what happens if you crowd Michael, which no one ever did........before Tyson.
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Unless he can stop Leon with one punch, Michael would have his hands full. Leon, like Riddick Bowe, was his own worst enemy and had only one great fight. Leon was a very wild fighter. However, he had great stamina when he was in shape.
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Even though ALI was old and untrained, Leon gave ALI all he could handle. Leon didn't have a bad chin either. His biggest problem was that, like Bowe, he won the title and lost his mind all in the same night.
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If Leon was in shape and motivated, he'd stick close to Michael, rob him of any room to punch and leave him wondering if anyone identified the guys who mugged him.
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Leon W15.
I consider Michael to be the better boxer, and would win a decision.
15 Rounds at Heavyweight