Originally Posted by toly
Definition: The Target Plane is the plane that includes the tennis ball at contact and the imaginary target inside of the deuce or ad tennis court. This plane should be parallel to the perpendicular to the racquet string bed during the impact. The Target Plane basically determines the boll velocity direction. We shouldnít change amount of the arm pronation, because it is almost impossible to control, in order to change bollís direction. Itís much easier to alter direction of the Target Plane. Always keep the range of the arm pronation around 90į.
Letís analyze Stosur and your arm actions before contact.
In pic.1 Stosur longitude axis of the racquet is parallel to Target Plane. In pic.3 longitude axis is perpendicular to the Target plane. She rotates her racquet by using internal shoulder rotation (ISR) around 90į.
In pic.4 longitude axis of your racquet is already perpendicular to Target Plane. Thus you cannot use, before contact, internal shoulder rotation at all. Thatís why you apply ISR after contact, but that doesnít make any sense. With this technique you never are going to get powerful and consistent serve.
i think toly's analysis can also explain the shallow drop... notice that stosur drops into the slot in a way the her hand goes back somewhere between her right ear and right shoulder.
Jack, your hand is OUTSIDE of your right shoulder.... it's humanly impossible to achieve deep drop that way.
I think you can try to feel the other extreme this way... imagine your right hand holds a comb and will comb the back of your head... this will allow you to feel how to bring the hand more inside (of the shoulder), to allow you drop deeper into the slot.