There is a very common instruction you will hear among coaches. "Swing down. Hit the ball on the ground" This is great for lower level players because it relies on the defense player not having the skills to make a play. In the pros though it simply is an out.74% of the HITS in the MLB last year were in the air. So how do you do this? Simple swing up. We call it driving the car.
If you have a launch angle below 5 degrees or less you will produce a ground ball, 10 - 20 degrees you will hit for average and 25 - 35 degrees power.
So what about back spin? If a pitcher wants to throw the ball as hard as he can does he do it back cutting the back of it or getting behind the ball.