One basic fundamental that has been left off is the type of swing and how the bat is making contact with the ball. It seems he is hitting the tophalf and or center of the ball when he not only needs to hit the bottom half but more importantly swing slightly downward in order to create backspin and get lift. Without back spin your ball is going to line-out on you and most likely, create top-spin thus creating the ball to loop hard as in tennis forehand returns causing downward tragectory. Most hitting instructors teach a slight downward swing with a finish up with both hands behind the front of the head. That is unless your a Ted Williams advocate which is more of a level approach.