As I write this I am watching one of those ESPN Classic programmes on boxing, replayed on the Canadian sports network TSN. It is a program called The Stylists, part 2 of a series. Part 1 apparently was called the Punchers, both about heavyweights. Later episodes were about the lighter weight classes. The series looked to have been produced in the 70's.
There were some interesting clips of old Jack Johnson fights, showing him dominate Tommy Burns and other smaller men. It also showed parts of the Tunney-Dempsey fight with the "long count".
In a 1947(?) fight between Jersey Joe Walcott and Joe Louis, Walcott knocked Louis down twice. At the end of the 15th, Louis started to leave the ring assuming he'd lost. But he won a split decision, as the camera showed 2 of Walcott's cornermen holding their heads in disbelief. Then they showed some of a Walcott vs. Ezzard Charles title match 4 years later, where Walcott knocked out Charles with an impressive punch.
The program then showed parts of. 3 Ali fights.(I assume they skipped the Marciano era because he was in the Punchers program which I didn't see.) It showed Ali winning the title from Liston, then in fights with Cleveland Big Cat Williams and Zora Folley, all in the 1960's before his 3 year layoff. My bias toward Ali is known here, but it really did strike me how much bigger, faster and better he looked than the guys in his bouts, as well as Walcott and Charles who were shown just before. It was like watching a great leap forward in boxing, kind of like seeing a young Michael Jordan right after watching players from the 50's in the NBA