Hi,

Here are some key points of man to man defensive structure.

• Communication is crucial, make sure your team are constantly telling each other who they are marking. It is also the full-backs job to tell his team where the gaps are in the defence are and what opposition players are not being marked. It is important to know and use each other's names so it doesn't get confusing.
• You should match the opposition in terms of size and speed. This means forwards should work in closer to the ruck to defend their forwards and backs should work away from the rucks to defend the opposition backs.

If the opposition has an overlap it will not be possible to man mark, in this situation you should not rush up at the attack but direct the to the touch line. It is okay to give up territory in order to drift to cover the attack. 

Also, around the break down it shouldn't be about man marking but marking the space/channel. At each ruck, one defending player should nominate himself as the 'guard'. And it is his job to ensure the opposition 9 or a forward pick and go doesn't get through.

I hope this helps!