Your right. Reality could be that Yaz has maxed out his cardio vascular system and it is good as it is going to get. Everything reaches a point of diminishing returns, so, no matter how hard you work at something you may not get much better.It could also be the case that Yazdani is just physically unable to match David's pace, no matter how hard he trains. David's pace for a big man is unparalleled and he is the only wrestler who has been able to completely gas Yazdani (twice). It has to be nerve wracking for Yazdani knowing he might gas again on the World's biggest stage. We will see how both of them handle the mental stress of this match. I expect to see a phenomenal match, and I could see either winning depending on the flow of the match and the potential for a catastrophic mistake, being tossed to their back, etc. I am so excited and nervous for this match!
For most people, no matter how hard you work at it, you will never be as quick as RBY. Same as, no matter how hard you work, very few people have the physical capability of ever running a four minute mile.
Obviously to be great at something, you need to put an enormous amount of work it to it, it also requires a large amount of natural ability too.