The first step to being able to score off the dribble is learning to handle the basketball really well. If you are having to worry about dribbling the basketball, then there is no way you are going to be able to get into your shot and shoot with a high percentage. That is why for this basketball drill you are going to work on ball handling, and then getting into your shot off of the dribble. You need to be able to handle the basketball at a high level so that you can focus on making your shot, and not on dribbling the ball.
The idea behind the killing the grass drill, is to have the player dribble the basketball as hard as they can and if they lose the ball that is okay, because they are getting out of their comfort zone and getting better. When they handle the ball in a game situation their hands will be quicker and it will be easy to dribble at game speed.