I can see your point, where is the space and how to attack it. And how to communicate? I actually do not believe there is a way to do this, I think you have to learn your players to adapt to the defence, spot the space and know to attack it. For all players to be tuned into the same idea you have to provide them a reference.
We have a interesting take on this, the following link discusses both a declarative knowledge (knowing what to do) and procedural knowledge (knowing how to do it). Both with the ball or as supporting player or as a defender. This is the theoretical context for playing together. http://www.rugbycoach.com/club/tacticalskill.htm
What is next? We give the players references through what we call a "family system". Depending on the position on the pitch and in reference to the ball, you are part of a family. Each family has a specific task and players within that family specific roles. There are four families:
1. Player with the ball and those close by: their goal penetrate to the defense
2. Early support, those players outside, ready for the next phase
3. Late support, players who where in a scrum/line-out
4. Deep support, 2-3 players behind the first family (not the full-back, he is deeper)
I even have a clip of Pierre Villepreux explaining the system to an Under16 side: http://www.rugbycoach.com/podcaster/
It helps the players with their decision making and positioning. Learning this family system requires a game based learning approach. We have a whole programme with supporting video clips etc. We now see our players not simply chasing the ball but making quality decisions in positioning, these are U14's too....
Let me know if you are interested, we are more than happy to come to RSA and help you!