the ball is moving. but so much of the tennis i coach to the league players is occupied with their quest to aim the ball.
my message to them is that it is better to think in terms of making good contact with the ball in a repeated fashion. once the player can make good contact with the ball time after time then they will be able to better aim the ball as they can feel the ball better and their brain takes over in hitting the ball.
so, do not worry about where you are aiming nearly as much as you worry about making good contact with the ball. the aiming 