Being able to run up the floor at full speed while dribbling a basketball and making change of direction moves is not something that just happens for most players naturally. It is something that needs to be worked on and developed on a regular basis in your basketball training. The value of being able to do this, is that the player will be able to maneuver through transition and get some easy fast break points, or get up the floor and set up a teammate for a good shot.
The 1 dribble behind the back change direction drill is going to help the player work on their handles at full speed, and also help with doing some conditioning as well. It is important to remember that it is okay to lose the basketball when doing ball handling drills. The reason why is because it shows that the player is pushing themselves to go their fastest. If the player is only going through the drill at half speed they wont get as much out of it.