They further teach for the man to place his right hand in the middle of the lady's back, not on her shoulder blade.
Many students first learn the basic swing rock step in class as a 'move back' then a 'move forward'.
When dancing with a partner you may find that this leaves you jerking your partner or positioned too far apart to control the next step. An instructor may show you a different way to perform the rock step 'change weight' without moving the body back and forward by keeping the step under your center. If you understand the technique from class, and can execute it, then take it home and practice it. Do not rock backwards more than six inches when you rock step. That is, rock back so that the toe of one foot is even with the heel of the other foot.