Mike Tyson: 8 fights, starting with Trevor Berbick ('86), going until Michael Spinks ('88). That said, one could easily define this as starting before the Berbick fight. Tyson was the best heavyweight in the game from his very first professional fight until the Spinks fight, and maybe even the next two past that, even though he wasn't being properly trained and it was just a matter of time before he got exposed.

pre-ban Ali: 10 fights, starting with the first Liston fight ('64), until Zora Folley ('67). This man was completely untouchable. Took very few direct shots in any of these fights. His fight against Cleveland Williams is poetry in motion.

Young George Foreman: literally 3 fights. Frazier, Roman, Norton. His next fight was in Africa against Ali, who exposed his weaknesses and sent him into a deep depression. He was never the same.

Sonny Liston: I'm not as knowledgeable with Liston. He was never the same fighter after the young Cassius Clay just comprehensively dismantled him in Miami. How far back before the two Patterson fights was Liston's prime? Anybody?

Jack Johnson: I have no idea how you define this guy's prime. The problem with Johnson is that he simply didn't train. He was so much better than everyone physically that he wouldn't train, and he also made no attempt to knock guys out. I'm a huge fan of Jack Johnson, but his career is a bit frustrating. He was the best boxer in the world and he treated boxing like a hobby. Banging white women was his full time job.

Joe Louis: 1937-1941. 21 fights, but this also included the famous "bum of the month" club. So, not all those guys were particularly good boxers. I think Joe Louis is overrated historically. He didn't dominate guys that a great heavyweight would have dominated (see: Braddock, James).

Joe Frazier: His prime comes to an end when young George Foreman just annihilates him in the "Down Goes Frazier" fight. It is really frustrating that he never fought Ali in the 1960s. Had Ali had two or three more fights, one of them would have been against Frazier, who was rising up the Heavyweight ranks. Frazier was the best fighter in the game from when Ali was forced to stop fighting in 1967 until Foreman dominated him in January 1973. So I'll call his prime the 13 fights between Chuvalo and Stander.

Larry Holmes: most underrated heavyweight of all time. Was the best fighter in the game from 1977-1984. Didn't get enough respect because people were still obsessed with the mystique that was a completely washed-up Ali. And gets overlooked historically because he came between Ali and Tyson. Had to beat an Ali that had no business getting in the ring with Holmes in 1980. I'll call his prime as starting with the Earnie Shavers fight in 1978 just because that was the first guy he fought that was worth a shite. His prime ended when Michael Spinks beat him in 1984, unless somebody wants to advance an argument that he was thoroughly done at some point before that.

Lennox Lewis: I think Lewis was still in his prime when he retired. I'm not sure when he started his prime. Was the first Oliver McCall fight an anomaly, or was he just not that good yet? I think it is difficult to define Lennox's prime because he so rarely fought. From 1993 on, he was fighting an average of two times a year. Any Lennox fans on here? Help me out. I also think Lennox is a tough fighter to define historically. He was the best fighter in the game for 10 years, but you look at his record and it is a bit underwhelming. Why did he never fight Riddick Bowe?

Thoughts? Other?