The slice backhand needs a full unit turn, just like all ground strokes. Look how coiled Arazi is in this full prepartion frame. Good reference points for the full coil are:

1. Your chin should be touching your hitting shoulder.
2. Your non hitting hand is on the throat of the racket.
3. Your wrist is cocked up, creating an angle to your forearm.
4. The butt of the racket is pointing straight out to the side and the non hitting side of the racket is directly facing the back fence.
5. Arazi has all his weight on his front leg, which is bent.

Note the same reference points for Hewitt. His chin is touching his front shoulder. His opposite hand is on the throat of his racket. His wrist is cocked up creating an angle to his forearm. His weight is loaded on his front foot and his knee is bent.