There is far more footage on Johnson than Corbett, and in much higher quality, which gives him an advantage. Having said that, I can't imagine Corbett was more skilled than Jack Johnson because of how good Johnson was.
Johnson was a technical marvel. Few understand what they are seeing when they watch Johnson. Amazing skill at a very high level. Control, control, control.
I guess Corbett had to depend on his skills more at heavyweight, being as he was generally the lighter fighter, wheras Johnson had advantage of being bigger and physically stronger, so had those attributes to fall back on also. I feel we did not see the fullness of Johnsons skills as he had tendency to not display them fully, often preferring to just do enough to win, sometimes that resulting in earlier fights which he lost due to coasting.
