Awesome stuff @kingraph! I agree with everything you've described here. A few thoughts of my own:
You're absolutely right that most of the "A" level players already have the knowledge parts down, and like you said there are still some players that are slightly better in the knowledge or I'm just going to call it the "skills" department. I think the biggest thing that sets the elite apart from the rest is the mental game. For lower skill levels, I would say that results are 80% skill based and 20% mental. Usually the higher skilled player will win the game and the bigger variance there is in skillset the less mental effort is required to win. What I mean is an A level player will have to focus a bit more to beat a B level player than they would to beat a C level player. As the skill levels increase, and the variance between skills of the opponents decrease there's a huge shift in the skills/mental breakdown to where I think results become based on 20% skill and 80% mental. When it's the best guys playing the best guys, it is a gruelling mental game. They both have the skills to know how to score and how to defend, it really comes down to who has the stronger mental game. Most goals aren't determined by a higher skill level, they're usually caused by one of the opponents making a mental error. I know for me personally the difference between me feeling mentally strong vs not can mean the difference between winning by 5 goals or losing by 5 goals vs the exact same opponent. I think the best of the best are where they are because of their mental strength. They have the ability to get "in the zone" and stay there for the duration of their game/series.
I compare it to Tiger Woods in his prime. He was the best because of his mental game. Every player on tour can hit it 300 yards and never miss a 2-putt. So there's not a huge difference in the skills, its the mental game that sets the elite apart. If Tiger had the lead on Sunday, it was an automatic win. He intimidated opponents with his mental game.