1. Drifting into the block shadow : Defenders instinctively take shelter behind the blockers instead of positioning around the block shadow — leaving the cross-courts and off-the-block trajectories open. Hebert: "creeping into the block shadow".
2. Faulty reading : The defender locks onto the ball instead of following the sequence "ball → setter → ball → hitter". Result: they guess instead of reading, and aren't stopped or balanced at the moment of contact ("stopped and balanced at the moment of contact").
3. Libero out of depth : Too close to the net, they can't defend deep spikes; too far, they miss the tips. Rule: line up your outside shoulder with the inside shoulder of the middle blocker, 6-8 m from the net depending on the block.
4. Defending setter unprepared : Stance too low or oriented wrong, preventing them from seeing ball + opposing court; premature start toward the target creating a Z1 hole; no "release call" signaling they're leaving the defense.
5. Overlap faults : Most common: Z6 drifts in front of Z3, Z5 ends up right of Z6, and the setter leaves too early to penetrate (fault #1 in 5-1). At the instant the server contacts the ball, every foot must respect front/back and left/right relationships (Rule 7.4).
6. Forgotten reception → defense transition : Players stay frozen in their W reception formation instead of shifting into base defensive position the moment the opposing setter touches the ball. Hebert: "sluggish recovery after play on the ball".
7. Bad zone 6 management : Confusion between "6-up" (rotation), "6-back" (perimeter) and "6-deep". The Z6 player must shift laterally based on the opposing attack side, not stay centered. Leaning back to dig puts the weight on the heels and kills reactivity.
8. Failed defense against the quick : Reading the opposing middle too late; back-row not moved up (on a quick, Z1 and Z5 must gain a meter toward the net because angles are shorter); "false stepping" (first step backward) loses available time.
9. Orphaned tip coverage : No defender explicitly assigned to the tip; "standing up on tips" — the defender is low for the spike, then stands up and extends their hands on the tip, letting the ball drop right in front of them. Focus must stay on the spike in a low stance, with a tip jump available.
10. Collective silence : No calls ("tip!", "line!", "out!", "mine!"); blockers who don't communicate their line vs cross orientation; no rotation captain checking overlaps before the serve.