Center cue ball control is where the cue ball rolls about 6" inches past the cue ball with a medium or hard hit. If you know where tangent line will strike the rail, the "center ball" hit will go forward a few inches on rebound. If you take a ball and have it forward of the 8 ball mark about a ball. IF you can make the ball and hole out the cue ball, you've got it. Great shape can occur with this knowledge.