The Data Blind Spot of Vietnamese Volleyball

THE DATA BLIND SPOT OF VIETNAMESE VOLLEYBALL Da Nang, 10:47 p.m., an April evening. I had just finished running the same script I have rewritten for seven years, pulling match data from a national championship group-stage game that ended three hours earlier. The screen returned a table. Column headers. Match ID. Two team names. And in every other cell: blank space. Not a single percentage. Not a single scoring timestamp beyond the three sets. The spreadsheet was as clean as a fresh sheet of paper. I sat back, poured another cup of tea, and realised I had touched this feeling for the third time in my career. The first was the summer of 2026, which I called the empty summer, and which produced four months of writing under the title The Ball Falls Silent. The second was a September night when I tried to reconstruct a first-pass efficiency index for a women's final and discovered nobody had recorded it. The third is tonight. Three occasions, three different causes, one identical result. And the thing I want to put on the table is not how to fix the script. It is this: if Vietnamese volleyball data keeps coming back empty at precisely the points that matter most, then what exactly are we analysing? CONTEXT: THREE TIERS OF A DATA SYSTEM To understand why an empty table is serious, you need to see what Vietnamese volleyball's data system is built from. At the basic tier, we have enough. Set scores, point totals, the names of scorers on the paper scoresheet, service errors, successful blocks — all written by hand at the scorer's desk in each arena, then re-entered into the organisers' summary sheet. This is the media tier. It answers exactly one question: who won, and who scored how many. At the middle tier, we have little. Spike success rates appear from time to time, but with no consistent convention between competitions, between generations of scorers, between matches. A spike blocked back that a teammate then saves — how is it counted? Depends who is writing. A set delivered too low, forcing the opposite to attack out of system — is that penalised? Usually not, because the scoresheet has no cell for it. At the advanced tier, we are close to blank. No positional first-pass efficiency metric. No hitting map for a single attacker across a season. No measure of set quality. No rotation-level data detailed enough to identify which team collapses in the two-attacker rotation. I have worked in sports data analysis in Vietnam since 2026. Seven years is enough to learn one thing: most of an analyst's time here is not spent analysing. It is spent hunting for data. And when the hunt fails, there are two options — state plainly that the data does not exist, or construct something that sounds plausible. I have seen both. Only one of them is science. There is a paradox I want to place here before going further. In the past two decades, Vietnam's women's national team has produced milestones that, in any other volleyball nation, would have been dissected across hundreds of pages of statistics. In May 2026, Vietnam beat Thailand 3-0 in the SEA Games 31 final at Dai Yen Arena in Hanoi. On 7 July 2026, in Manila, Vietnam beat Belgium 3-1 to win the FIVB Challenger Cup and earn a place at the 2026 Volleyball Nations League — the first time in history. Those two matches are achievements. They never became data. Based on my own tracking experience, no public advanced-metrics set accompanies either match to answer the simplest question: why did that team win? We have memories, video, and plenty of emotional commentary. We do not have a table. THE ARCHITECTURE OF AN EMPTY TABLE An empty table does not appear from nowhere. It is the endpoint of a chain of decisions, and every link in that chain can snap. The first link is the source. A competition website may not publish detailed scoresheets, or publish them days late, or publish them as scanned images a machine cannot read. The second link is format. A scoreboard photographed on a phone, sent to a group chat, then typed by a volunteer into a spreadsheet — each pair of hands a column of numbers can pass through is a chance for loss. The third link is convention. If the person recording at the arena defines a good pass differently from the definition my model assumes, then the data still arrives as broken data wearing the costume of clean data. Those three links explain tonight's blank space. Not because the match had nothing to say, but because the match's story was never recorded in a form a machine can read. There is one detail I always remember when I think about this. In 2026, as an intern at a football analytics startup in Da Nang, I calculated expected goals for a V-League club after round 12 and concluded their third place would not hold. The report was withheld, because someone feared it would damage a broadcast contract under negotiation. By season's end the club had taken four points from their last eight matches and dropped to ninth. I tell that story not to prove the data was right, but to say that even when data exists, it can go unused. With volleyball, the problem is one step earlier: the data never existed. THE DATA BLIND SPOT I spent most of last season counting what cannot be counted. Take a concrete example. A women's team in the national championship plays roughly eighteen matches a season. Across those eighteen matches, I want to know: in the two-attacker rotation, how much does their attack efficiency drop compared with the three-attacker rotation? This is the most basic tactical question in modern volleyball. It determines who a coach places opposite whom, and which team must sacrifice an attacker to protect its defensive system. I cannot answer it. Not because it is difficult in principle, but because rotation data does not exist in public form. To get it, I would have to rewatch all eighteen matches, rewind every rally, identify each team's service order myself, and record who stood where after every court change. Eighteen matches, roughly one hundred and eighty rallies each. More than three thousand rallies. For one person, that is three weeks of work. I tried it with a single match. It took four hours. I got nearly all of it, but by rally one hundred and seventy I was no longer certain where the setter stood in the fourth rotation. The footage was not wide enough. The cameras follow the ball. This is a miniature of an entire volleyball culture. We have footage, but the footage is shot to serve spectators, not analysis. We have scoresheets, but scoresheets are designed to confirm results, not to reconstruct process. And when a sport has no process data, every argument about it ends in feeling. Someone says that opposite hitter played badly. Someone else says she was abandoned by her setter. Neither is wrong, neither is right, because no sufficiently neutral third party exists to adjudicate. This is especially unfortunate when you look at the names who have gone further than the domestic system. Tran Thi Thanh Thuy played in Japan, then moved to Turkey with Kuzeyboru from 2026 — in those leagues she is measured by metrics nobody at home records for her: attack rate by net zone, reception efficiency against heavy serves, times blocked within a weak rotation. Nguyen Thi Bich Tuyen rose to prominence with LP Bank Ninh Binh through a weapon that is easy to see with the eye but very hard to prove with numbers, because we lack the tool to prove it. They bring skills home. We do not bring home the methods that measure those skills. THREE TIMES I TRIED TO COUNT AND FAILED The first was the summer of 2026. Domestic volleyball stopped, and I built a small model of hamstring injury risk after a long layoff, based on training diaries from a handful of teams. The model predicted correctly for six of eight teams when play resumed. But its input data came from coaching notebooks I had to request through three layers of relationships, each written in a different style. The result was right. The method was not repeatable. To me, a result that cannot be repeated is still just a beautiful anecdote. The second was when I tried to build a first-pass index for a women's final. I split every reception into four grades: ball delivered to the ideal spot so the setter can run the full attack menu; ball delivered to the right spot but the setter must move; ball returned high and far; ball lost entirely. After the match I compared with the official scoresheet. It recorded only good pass and bad pass. Two grades. I had four. There was no way to reconcile the two systems, and no way to know where that night's scorer drew the line for good. The third was tonight, when the script returned blank space. Those three occasions taught me something I dislike writing down, because it sounds like an excuse: in Vietnamese volleyball, an analyst must work two jobs at once. The first is to find the truth. The second is to build the tools for finding it. And the second always consumes the time of the first. A COUNTER-INTUITIVE VIEW Here I have to warn myself, because this is the easiest place to slip. When data is empty, there is an enormous temptation to treat the emptiness as evidence. This team has no good numbers, therefore they do not play well. Nobody records her digging stats, therefore she does not matter. That is the most basic reasoning error in the trade — converting the absence of data into a conclusion about reality. An empty table does not say the other team played badly. It says we have not measured them. Those two sentences differ in substance, but to most eyes they look identical, and that confusion is the source of most of the hasty conclusions I read every week. The second point: correlation is not causation, even when the number is beautiful. A team winning twelve straight matches can be credited to a new tactical system. But if, over the same period, they only faced opponents who were weaker physically and missing a key player to injury, then that number is measuring the schedule, not the tactics. In a league with an uneven calendar and a small sample of matches like ours, separating those two things is almost mandatory before saying anything at all. The third point, and perhaps the one I believe most: the emptiness of Vietnamese volleyball data is not a catastrophe. It is an unopened research programme. Every blank cell in my spreadsheet is a question that already exists, waiting for someone patient enough to sit and count. Where statistics are thin, people are forced to look more closely with their eyes — and the craft of watching tape, which I have practised for seven years, was born precisely from that scarcity. We are not weak because we are poor in data. We are poor in data, and that gives us the chance to do something nations flooded with numbers long ago stopped doing: define our own metrics, instead of importing them from elsewhere and then struggling to explain why they do not fit domestic reality. WHAT MY DATA LEANS TOWARD Tonight, instead of fixing the script, I opened the match footage and counted by hand. One match. One metric: the number of times the home team was forced to attack out of system after a substandard reception. I counted twenty-three. The official scoresheet recorded that team's attack efficiency at fifty-one percent — a number that sounds robust. Twenty-three out-of-system attacks are twenty-three occasions when the attacking play was broken before it formed. Nobody records them. Nobody subtracts them from efficiency. And so that team walks into its next match carrying a sheet of numbers prettier than reality. My data leans toward a small conclusion, and I keep it small: in Vietnamese volleyball, we do not lack analytical intelligence. We lack people willing to sit down, rewind the tape, and write into an empty cell a number nobody asked for. That work is unglamorous, generates no headlines, and almost nobody pays for it. But it is the only thing that distinguishes a volleyball culture that is improving from one that is merely retelling itself. One question remains unanswered, and I leave it here like a cup of tea inviting the reader to sit down: if next season we could choose exactly one advanced metric to record for every match, which should it be? I have my own answer. But I would like to hear yours first. SIGNALS FOR THE NEXT ROUND Three signals I will be tracking. First, whether the national championship organisers publish electronic scoresheets in a machine-readable format. This is the cheapest change with the widest reach: it requires no ball-tracking technology, only an administrative decision. Second, whether clubs begin hiring their own statisticians. A club with one person counting first passes all season holds a decisive information advantage over a club that only reads the organiser's scoresheet after the fact. Third, whether the national teams bring home the metric sets they are forced to use when competing on the continental stage. International experience brings back two things: results and methods. The second is usually forgotten, and it is the one that lasts longer. I keep a small hermitage where volleyball and data bow to each other. Tonight that hermitage is empty. And I am still sitting here, waiting for next season to blow fire into the spreadsheet one more time.