Sweeper/Stopper is a good defense at times. It has a "safety" who can in-a-way sit back, view the field, and jump on anyone who gets past the fullbacks or stopper. The sweeper has be to athletic and be able to read the field very well. He/She HAS to control the FB's & Stop. It's run with a Man/Zone combination at times. I like it, but then again I don't. I like that the strikers get to be marked and don't have any room to breath, but if the ball is played to a corner, then both the fullback & sweeper could be out of the picture leaving the defense hanging.
The flat four has to have a lot of communication. If you have speed then the off-sides trap could possibly be attempted which is good to use (if the officials actually know how to call it). FF covers more space on defense. Sideline-to-Sideline is covered. Through balls are a demon to deal with, but are no worry if the Keeper or CB's are quick. What can make or break the flat are diagonal runs. Good defense and used for AGES.
Questions to answer is how strong is the midfield? Strong midfield then run a Flat Four. If the midfield is weak, the clog it up with a Sweeper/Stopper.
