The drag back is a favourite of Robin Van Persie and my team mate DJ Alex O'Keefe, who use this technique to open up space to pass the ball towards the wide areas of the pitch.
By practising the drag back, you will increase your confidence to take the ball away from your opponent and change direction of the ball to either dribble, switch play or have a shot at a goal.

Open up the image to the right and see exactly what I mean.....