Rehearse beside the ball to check your low point
Before the pitch, the instructor rehearses beside the ball to check where the club is bottoming out. He makes tabletop practice swings and watches where the club grounds relative to the ball; if it strikes way behind the ball he knows he is moving off it, so he keeps swinging until the club consistently grounds near the ball.
Channel: Danny Maude
Watch official source at 3:24Why this context matters
A pre-shot rehearsal done to the side of the ball, not the shot itself.