I absolutely despise zonal marking and how it was brought in was beyond me. All the training and education I ever had growing up there is only 1 way and thats man marking, pick your man, for the next 90 minutes he is your man, don't give him an inch. Win your battles. Let him know your there. And When you attack the ball, communicate with your team to cover your position. It is that simple. Zonal marking where your marking space and trying to predict the next move is poor. The amount of times watching City where they had a free kick inside our half, Cyrus Christie for example would be 5-7 yards away from his wide man watching him, the wide man would have his hand up in the air and the free kick would come straight over to him, Christie then closes down, whips the ball in and they have a chance and on some occasion I remember, score. Well you would generally nullify that by man marking and winning the header when the free kick comes!