What is your preferred positioning when man marking during corners? If you are in front of the attacker (ball side and goal side) is the priority to face him/her or to be able to see the ball kicked and then react?
My preference for marking is always being in a position to see both the ball and the opponent I am marking. As an attacker I exploited poor marking with blind side runs constantly.
I think it is best to stand slightly on one side of the marked player and see the ball coming. But it is above all the speed of reaction which allows a defender to be good in this area without forgetting the physical capacities (jump, flexibility and body balance)