Vietnamese Volleyball and the Data Vacuum: When There Is No Record, Referees Rule by Memory

I was sitting in the fourth row, left corner of the stands, the seat that looks straight into the net. Fourth set, 22-21. The twenty-third rally: the home team's middle blocker swung into the block, the ball deflected out of bounds. The first referee raised an arm, point to the visitors. The home coach shot to his feet, palms open, eyes searching for the line judge. The line judge shook his head. No screen in the arena, no slow motion, no touch log. Only the whistle, and after the whistle a ruling that closed every argument.

I wrote in my notebook: “Rally 23, set 4, block touch or not, no data to cross-check.” Thirteen years of watching domestic volleyball, that is the line I have written most often. Not because my eyes are weak. Because the competition does not keep a thick enough record for anyone to check twice.

At FIVB level the story turned another way in 2026, when the Challenge system entered international events such as World League and World Grand Prix. A team may request a review of four situations: ball touching the block, net fault, foot fault, and ball in or out. Cameras rebuild the ball's trajectory into a three-dimensional projection, the referee reads the result on the big screen and signs the scoresheet. At Vietnam's national championship, at the VTV Cup, at youth events, that tool does not exist. Referees still work with the naked eye, and the match record still holds only set scores and the list of sanctions.

I was thrown out for reading the rulebook correctly. Luckily, some things only become clear from outside the door.

What I see most clearly, after more than a decade of note-taking, is that the gap sits a layer deeper than any single rally. A volleyball ecosystem that does not store data has no way to correct itself, because it has nothing to compare against.

In developed competitions, analysts work from a fixed set of metrics: side-out rate, perfect pass rate, attack efficiency calculated as kills minus errors over total attempts, blocks per set, and the ratio of aces to service errors. Those numbers are not decoration for a broadcast. They are diagnostic instruments. When a team gets stuck in a rotation with two attackers, the coach reads the sheet and knows immediately whether the cause is a poor first pass, the setter's distribution, or a middle blocker who cannot find the timing.

Without that set of numbers, Vietnamese coaches have to diagnose by feel. The video exists, but video does not count itself. If nobody counts, nobody can compare one rotation with another, one match with another, one season with the last. A substitution gets made on instinct rather than data, and three weeks later nobody remembers whether it was right.

For referees, the consequence is heavier. When error leaves no trace, every decision dissolves into memory, and memory cannot be cross-examined. In 2026, when the pandemic forced competitions to pause, I was assigned to review all 182 matches of the 2026 season. I compared each referee's card rate against the number of spectators in the arena. One referee issued 23 percent more cards than the league average in front of a full crowd, but 12 percent fewer in an empty stadium.

In an empty stadium, I have seen referees tremble. Not from pressure, but from the absence of actors for them to perform for.

That 14-page internal report was dismissed as over-interpretation because the sample was small. I did not argue. I extended the comparison across five seasons. When VAR turns its lens on a remark, I do not argue. I let the camera testify. With data, the only way to win an argument is to make the sample large enough.

At the selection layer, the data vacuum produces a subtler effect: it pushes decisions toward criteria that are easy to see. Height, club results, connections, and the gut feeling of whoever sits in the hot seat. When a player like Tran Thi Thanh Thuy goes abroad, she enters an environment where every spike of hers is logged and every reception rate is calculated. At home, girls of the same generation do not get that luck. They are judged by eye, and the eye is biased.

At the media layer, a poverty of data produces a poverty of narrative. Television needs numbers to build drama: who leads the league in attack efficiency, who just broke the record for blocks in a single match. Without numbers, commentators have only two moves, praising the winner or scolding the loser. Sponsors read the same tables before they commit money. A league that cannot measure itself will struggle to sell itself.

The first reflex is always to call for a Challenge system. But Hawk-Eye does not answer why you lost the fourth set. The machine only answers whether the ball touched the block and whether it landed inside the line. That is a true-or-false test of one instant, not a map of an ecosystem's development. The installation and operating cost of such a system far exceeds the budget of most domestic clubs, and even where it could be installed, it would still produce no metric a coach could use in training the next morning.

The work actually required is far cheaper and far duller. One person, one laptop, one spreadsheet open through the match. Log every rally: rotation, serving team, quality of the first pass, attacker, outcome. The first three columns are enough to expose a stuck rotation. Five columns are enough to evaluate an individual across a season. No camera, no imported software, no budget.

The real obstacle lies elsewhere, and it is harder to say out loud. Data is a tool for auditing accountability, and not everyone inside the system wants that tool to exist. A coach protecting his job, an official protecting the calm, a referee protecting the freedom to rule unexamined. Without data, every failure can be explained by bad luck, by injury, by the schedule, by one controversial rally in the fourth set. With data, failure starts to have a specific cause, and a specific cause always finds someone to answer for it.

Rules do not feed people, but people feed the rules with model rallies. To have good rules, you must first have rallies properly recorded.

If from next season the national championship publishes a rally-by-rally log for every match, including rotation, first-pass quality and attack outcome, the fans' arguments will change tone within three seasons. People will stop saying the referee stole the win, and start asking why the side-out rate in rotation four dropped nine percentage points from the previous season. That kind of debate is far duller than a rage in the stands. It is also the only road by which a volleyball ecosystem grows up.