Stamina and strength are vital components of athleticism. I would point you to their role in Athletics as proof.
Good comment but Leonard vs Duran 2 is a bad example, Duran was winning before he basically just decided to quit
It is rare when i agree with you, but this is one of those times The only fighter i remember seeing Rocky against that made Rocky look more technically sound, was Rex Layne Lee Savold also wasnt anything to write home about, that fight was just a mess, Marciano had the flu and Savold was washed Also to give credit to Marciano, the fighters he fought when he was champion were extremely technically gifted (with the exception of C0ckell), and i think Ezzard Charles specifically has a very strong argument for being the best technical boxer to ever be heavyweight champion
As has been noted, you can't say that Marciano is both athletically untalented and technically inept. He had to win all those fights somehow. He was a freak.
I don't know if Duran was winning, but I agree his lack of desire is why he lost. However, the rounds Leonard was winning, were won by athleticism not skill IMO. He lost the first fight because he was out skilled by Duran, but he won the second by being quicker, and playing to his strengths IMO.
It honestly was not even close and Duran was in the process of being outclassed and that is why he quit. Hell Leonard was actively taunting Duran even winding up and nailing Duran with the other hand. Duran had no idea how to deal with it because he had never experienced it so he through up his hands and quit.