Concrete is how things are in reality. In badminton are these the shuttle, the court, the opponents with their rackets and oneself, all as these are really be seen.
When playing, all concrete aspects of the game are really perceived. When not really seeing how things are, but just thinking how they are, things are wrong estimated. The place of the shuttle and its pace, and the position, movements and stance of the opponents, etcetera, are reckoned to be in an other way than they really are. Then own strokes, movements and tactics are not well applied.

But, when playing, things won't be well seen all the time. That is because, when looking to one aspect, the others are perceived vague. Thereby, fantasy and thoughts are used to choose the right positions and places to hit the shuttle to, and this distracts the attention from the real, concrete play.

To realize a game with concretely perceiving all the aspects and yet using fantasy to play well, fantasy controls itself. It does so by comparing itself constantly with the concrete situation. That is done by playing with an open mind which makes possible to perceive the play as it really is. When the eye is directed to some particularity, the rest is perceived also, though vaguer. Fantasy then takes over partly for a moment. So stays the concrete court etc. constantly in mind. Concretely, looking at the shuttle and seeing it, looking through it, the rest is perceived too.

When well attentively playing, the aspects of fantasy and reallity merge together into a play, that then is experienced as one complete whole game on what is worked.

Understanding the above helps keeping the badminton game transparent.