I realised recently that sport is like n exam. In most exams it's not about how good you are at any particular subject. It's how well you answer the questions you are posedon the day. Nothing more and nothing less. Course work isn't so much like this.
In this situation you could know everything about the subject or sport. You could have all the answers, know all the shots, be the fittest and still lose or fail if you don't know how to make it work on the day.
That's what I was taught about exams. Don't assume they're an exact test of your ability. They're a test of your ability on the day and how well you answer a question, or set of questions you haven't seen before.
Sport is just the same. No matter how well you prepare you can still come up against an opponent who asks questions that you just don't know the answer to on that day. Any other day you'd win but not today.
So those who really reach the top learn that their ability to form the best answer from what can do or what they know at the time they're asked is what determines how high they rise. The more consistently they do this the better they're chance of being the best.