Empty Data and the Trap of Pretty Numbers in Vietnamese Volleyball

On Saturday night, I sat in the third row of the arena, holding a stat sheet printed in haste after the second set. The home team had a 68% perfect-pass rate, fourteen digs per set on average, and a libero noted as "the most consistent in the tournament." Looking up at the court, I saw the opposite: balls landing between two middle blockers, a set that never reached the outside hitter at position four, a back line retreating in silence. The paper said one thing; the court said another.

Under the arena lights, I find the stories the scoreboard never tells. But this time, even the stat sheet told nothing. It was merely pretty.

Vietnamese volleyball is entering an era in which data has become a form of power. The national championship is broadcast live, matches are recorded from multiple angles, and each team now has someone sitting behind a screen clicking counters. Coaches speak of "perfect-pass rate," "attack efficiency," and "blocks per set" as if these were eternal truths. Sponsors like the numbers. Fans like the numbers. And reporters like me are forced to live with them.

There is a paradox I keep meeting after seven years covering volleyball: the more data there is, the more easily people believe things that were never verified. I have received datasets so flawless that not a single cell was missing and not a single unit was off. When I asked for the source, the answer was: "We compiled it ourselves." From where, how, checked by whom — no one could say.

That is when I realized something that seems obvious yet is easily ignored: a complete dataset is not necessarily a correct dataset, and an empty dataset is absolutely not a basis for concluding anything.

Years ago, I spent nearly a week writing a tactical analysis from a data file that had been sent to me. The file was full. But when I opened column after column, I found mostly empty cells, a few repeated rows, no team name, no date, no opponent. I was tempted to "fill" the gaps with my own judgment. Then I stopped. Writing from an empty file yields only one certain thing: fabrication. I dropped the piece.

That lesson returns every time I sit before a volleyball stat sheet. In this sport, some metrics are born with holes in them.

Take "perfect pass." It usually measures just one thing: whether the ball reached the setter's hands. If it did, it counts. Whether the setter could turn that ball into a clean attack is not in the metric. A team can pass perfectly 65% of the time and still lose in straight sets, simply because every ball that reached the setter landed in a position from which no attack could be launched.

Take "digs." It counts the number of times a hand touches the ball, not the value of the ball after that touch. A libero dives, scoops the ball skyward, and the ball drops into a zone the opponent is waiting in — still recorded as a successful dig. The beauty of the action is noted; the pointlessness of the result is ignored.

Take "blocks." Many sheets count every touch of the hand on the ball, even when the ball still falls on your own court. A touch that loses the point can still inflate "blocks per set" into something handsome. And so the losing team ends up with a higher block count than the winner.

These examples are not scattered. They are linked by a common logic: metrics measure volume, not timing; the action, not the result; the visible, not the decisive. Running without purpose also produces pretty numbers — true in football, and no less true in volleyball.

Seven years of watching matches taught me that most decisive developments happen where there are no statistics at all. That is the libero's position before the serve. That is the setter's movement toward zone two to drag the opposing block. That is the moment an outside hitter at position four drops back to "sweep" in defense, a touch no stat records, yet one that keeps the team from losing the point.

Every court is a universe, and I am a man obsessed with connecting the constellations. The problem is that most of those constellations are invisible to a spreadsheet.

In a match in last season's national championship, I sat recording the visiting setter's position after every opponent serve. The visitors had higher attack efficiency and better passing on paper. But on close inspection, their setter kept having to leave position to handle high balls from zone six — meaning the back line was digging the ball, but digging it in the wrong place. The home team won, and on the stat sheet, they lost almost every attacking metric.

The revolution does not begin with the opening whistle, but with a quiet pass in the back line. I believe that, and I believe it enough to write it.

So where do these pretty numbers come from? Mostly from three places. First, club staff compile them themselves, and those who compile their own numbers are rarely impartial. Second, volunteer groups click counters under different definitions, so two sheets for the same match can diverge by ten percent or more. Third, the media repeats the numbers without stating who measured, when, and under what convention.

When all three lack transparency, what reaches the audience is a sheet that looks highly professional but cannot be verified. I call it empty data in the costume of full data. It is more dangerous than an empty file, because everyone knows to stop at an empty file, whereas a pretty sheet makes people charge ahead.

Here I look to Thailand — where I was born, and where women's volleyball built a rigorous data culture long ago. Thai clubs publish statistics with definitions, with a person responsible, and allow cross-checking. The gap between Thai and Vietnamese volleyball is not in height or vertical jump; part of it is in habit: Thais treat data as a shared asset, while we still treat it as an internal secret. That lesson must be translated for the Vietnamese context, not copied wholesale. A small club in Vietnam does not need an expensive system; it needs one honest record-keeper and one notebook that states the definitions clearly.

From there, I set myself a simple process when working with any dataset. Who measured it? Under what definition? Is there a second source to cross-check? What is the publication date? And finally, does the number match what I saw with my own eyes on the court? If the answer to any item is "I don't know," I slow down a beat.

A notable example of the value of verification lies in the VTV Cup — the international women's volleyball tournament organized annually by Vietnam Television since 2026. Over more than two decades, this event has generated a deep store of head-to-head data between national teams and regional clubs. But if someone cites a figure from the VTV Cup without stating the year and opponent, that figure is meaningless, because each edition has a different roster. That is the lesson of source context — something modern stat sheets often blur away.

The most counter-intuitive thing I have drawn: in volleyball, the team with better statistics is not the team that plays better, but usually just the team that touches the ball more. A proactive defense that ends rallies early will have fewer digs. An excellent setter who turns every messy ball into a point will have fewer pretty touches recorded. Efficiency, in the naive reading of a spreadsheet, gets punished.

And here is the deeper blind spot: we are teaching a generation of young coaches to read matches through metrics designed to be easy to count, not to be correct. A great blocking middle is not defined by successful blocks, but by how often the opponent is forced to change attack direction out of fear of him. No one counts fear. No one counts hesitation.

When an analysis is built on an empty data foundation, it is not wrong in the details — it is wrong at the root. Every conclusion afterward is merely decoration on a premise that does not exist. For a reporter, that is the greatest temptation: the feeling of having "grounds," when in truth one has only "form."

Tactics are poetry; you just need to know how to read between the gaps. But the gaps of empty data are dead gaps, not gaps to be read.

What I wish for Vietnamese volleyball is not more statistics, but better questions. Who measured? Under what definition? Cross-checked against which source? And most importantly — does this metric help me see what I missed on the court?

From the SEA Games to the virtual arena, the spirit of sport is still written in the same language. That language does not live in pretty numbers, but in the moments when we must stop and admit: I do not yet know enough to conclude.