As in our picture, the main idea is a position where the lower part of the cueing arm, together with the elbow is being placed straight above the cue.
But when we look around we notice a lot of players are not displaying this position, and still controlling their cueing direction. Basic rule here is that result counts over the arm’s position. When it is not entirely straight, but you control the cue ball well, there is no harm done. Simple as that!
The 90° angle of which we all talk about is being formed by the cue and the lower part of the arm ... not by the lower part and upper part of the arm. Small deviations to the 90° angle are allowed, as long as it has no negative impact on length of follow through anc cueing direction. The reason why this 90° angle is mentioned is easy to explain.
The elbow acts like a pendulum. And as we cue forward, there is only one brief moment in our swing the cue is not going downwards or upwards. Correct! In its lowest point of the swing. When you hit the ball at this stage the cue momentarily will go forward without having any intentions moving up or down, and so you cue with maximum output. When you hit the ball while the cue still has to go down or passed its lowest point, the cue will show both intentions forward and also upward or downward intentions. Your cueing intentions are divided in forward and downward/upward movement. With this for a fraction your cue action is lacking its maximum ability.