The Bottom Line... 1) Phil's coach's point was that you should neither concentrate on the tape nor aim down when trying to execute a good drop. 2) This is a matter of psychology rather than physics. The point is the mental context in which you hit the birdie. The coach just threw in the word physics to make it more convincing and to get his point across. He's just doing what he finds effective in getting proper technique ingrained into his students' brains. Believe what he says about badminton; take what he says about the physics of badminton with a grain of salt. 3) In the end there is no magical equation to help your badminton game. If anything, thinking about kinematics will just confuse you. For one thing, a birdie does not always travel in a parabola. That's the whole point of badminton. It's the only sport where the ball has very high air resistance, making it perform completely different from a regular ball. Just get on the court and the intuition you gain from practice will far outpace the benefit of any mathematical theory.
You are right, his instructor ignored psychology, mostly the topic of perceptions. On the other hand, he may be trying to give confidence to his students. But, this kind of confidence may be temporary as students later would try to question it, thus gradually weaken its effect. Unless this kind of explanations has good effect to confidence and improvement of skill, it may cause bad chain-reaction, which students would second guess his other comments too.
This is one of these very profound statements that is absolutely false. There are too many variable involved: contact point, follow through, racket speed, racket angle etc. etc. It is not a simple case of drawing a straight line from the bird to the floor over the net like a refraction problem in physics. Besides all of us are continuously proving him wrong every time we play by hitting into the net even though I am sure none of us does it intentionally.
