So, your approach is to set one defender per attacker in your defence and sacrifice the only ST to have one more man in midfield and you positioned him in such a way that he appears to be free to receive the ball to participate in your build-up from defense to attack while the other nearby players keep the opposing players busy (taken by zonal marking). What if the opponent uses man-to-man marking? This free player will be likely to be tightly marked then.