Many people are familiar with the diamond defense because it is often preferred on younger soccer teams, but once you get into the high school, college and professional levels, teams will start to play a flat back four.In a flat-back, the four players are responsible for keeping the offense out of the middle. Here are some ways to play an effective defensive game with a flat-back four.
Sweeper: One of your center backs will act as the sweeper. He will be the last line of defense and will sometimes have to drop back a yard or two behind the other fullbacks, However, he'll usually take that position when the team is on offense or when the ball is out of the attacking third, and then fall back in line the closer the opponents get to your goal.
Channel the offense: The term "flat back four" is misleading because one of the cardinal rules of a flat back four is "never be flat." Never stand in a straight line across the field. The defense should be lined up diagonally. This way the offense is forced to go where there's more space. Doing this will allow the defense to know ahead of time, which side the offense wants to go to. That way, the defensive mids can react accordingly.
Step up: When the ball is cleared, the defense needs to get out quick. Everyone should be up the field and ahead of the sweeper. Forcing the offense back up the field will prevent long runs and will also prevent any opportunities from the opposing offense if they boot it down the field quickly after it's cleared.
Zone Marking: There are several ways to play man-to-man in a flat back four, but the purest form will allow the defense to play zone. It's important for the backs to stay in position, so you can't follow one offensive player all over the field. You'll have to pass your mark off to another defender in order to make sure you don't get caught out of position.