Simply put, it’s believing your own eyes and coming up with your own, original thoughts.
If a player doesn’t look fast to you, but is widely considered so by everyone else, then don’t go along with it.
If a coach is quoted as saying something about a team or player that appears to you to be demonstrably false, don’t defer to his expertise. There are a ton of coaches in football, some bad and some good. Not all of them are right all the time, or else there would never be a mistake in recruiting.
If someone is considered a great player, but doesn’t appear to be up to snuff to you, then go against the conventional wisdom.
Above all, rely on your own observations to make your own, coherent opinions. As you can see down below, it can’t be any worse than what the so-called experts come up with.