Receiving the ball on the back foot with an open body helps the player to move off in different directions because they can see where the space is on the pitch and where to pass should a team mate be in a better position
Players need to open up their body to the pitch so they can see their opponents and their teammates. With open shoulders player can receive on their back foot which makes it easier to change direction when the receive the ball making it easier to go forward and attack the opposition goal.