Importance of teaching soccer players to Shift with the ball so they have "shape", "support" and "depth".

You must have a good Center Fullback and at least one good "Stopper" or a Center Midfielder who can act as a "rover" and drop back to help out the Fullbacks when your goal is under attack.

Soccer Tactics For Select Travel and High School Soccer.

Importance of soccer players shifting with the ball (Defensive Movement).

How Slow, Unskilled, Brave Soccer Fullbacks Can Be Successful.

The concepts of "Positions", "Support" and "Shift & Sag" teach teamwork.