Two players; one stands with his feet apart and the other is the hitter. The hitter throws the ball up to hit to the defender, who brings his feet together then apart again dropping and timing the drop so as to be in position just prior to the hitter hitting the ball and plays defence, keeping his chest facing the hitter and playing the ball in front of his body.
New hitters rarely miss because of their arm. They miss because of their feet. Build a reliable approach, then time it with your setter.
When your hitter gets stuffed, five teammates standing and watching is how you lose the point. Good attack coverage turns a blocked ball into a second swing.
Coaches spend hours correcting arms in serve receive when the real fault is almost always the feet. Fix the movement and the platform fixes itself.