A blog article provides a useful progression to think about defending in volleyball, though there are some fuzzy points in the systems side.
A fellow volleyball coach highlights a weakness of heat mapping to help decide what type of defense you play
At what point does it make sense to dedicate a defender to take tips, and thus forgo defending spiked balls?
Is it best to get great at one defensive system or to develop the ability to play multiple systems? I argue doing the first is basically doing the second.
Making your team strong in defense generally means addressing four primary areas of focus - blocking, system, digging, and mentality
How important is blocking in determining a volleyball team's success? It depends on how you define blocking and the level of play your team is at.