The system provides the benfits to only that certain ninja on that certain position, so the only team member that will benefit from each attribute is the one on that position.

Basically only that position 4 ninja gets the def and res, so if he dies, he just dies. The stats don't roll over to pos 3 for example.

in this day and age should had stacked pos1

No, the stats are only there for your position 4. If they are dead the stats are gone.