Measurable Bias: VAR, Workload and the Breathing Rhythm of the V.League Regular Season

Minute 78, score 1–1, a cross from the left swings into the penalty area. The visiting centre-back turns, his elbow swings out, and the home striker goes down like a tree cut at the root. The referee stands twelve metres from the point of contact, his line of sight blocked by one of his own players. He points to the spot after one and a half seconds. The big screen in the corner lights up with the familiar words, and the whole stadium turns to look at each other while the VAR team, in a room three hundred kilometres away, begins to rewind.

I sit in row seven of stand B, a notebook in my left hand, a stopwatch in my right. Three minutes and forty-seven seconds. That is how long the match stands still. In those three minutes and forty-seven seconds I write four lines: the moment of contact, the first camera angle, the deciding camera angle, and the moment the referee either upholds or overturns his decision. I started that notebook in the 2026 season, after a year in which I learned the most expensive lesson of my career: sport never forgives carelessness, and referees are no exception.

People tend to look at VAR as a mirror held up to justice. I look at it as a measuring instrument. A measuring instrument does not create justice. It only makes asymmetries that already exist visible, provided someone is willing to sit long enough to read the numbers instead of reading emotion.

The rhythm of a regular season

A regular season in V.League 1 is not decided by a single moment. It is decided by twenty-six rounds, by night flights, by recovery sessions at six in the morning after the squad checked into the hotel at two. With fourteen clubs, each playing twenty-six matches, plus the National Cup and continental competitions for those who qualify, the calendar can compress to three and a half days between appearances.

VAR has been deployed across V.League 1 since the 2026–2026 season, first at selected fixtures and then across matches at venues with the required technical infrastructure. That was an infrastructure milestone, and I do not deny its value. But I want to be precise about what I track: not whether VAR works, but how VAR operates differently depending on which team is under review.

Based on my own experience watching these matches across many seasons, I keep a four-column table for every VAR intervention. Column one: the moment in the match. Column two: the type of incident — goal, penalty, red card, mistaken identity. Column three: which team benefits from the final decision. Column four: the time between the referee stopping play and the ball rolling again. Those four columns are imperfect. But after seven seasons they produce a trend line I cannot ignore.

What the trend line says

From the opening round of this season to round fourteen, I recorded forty-seven direct VAR interventions in an on-field decision. Nineteen of them led to the original decision being overturned — a rate of roughly forty percent. That sits close to the average published by Asian leagues, so in itself it is unremarkable. What is remarkable is the distribution.

Of those nineteen overturned decisions, thirteen favoured the team sitting in the upper half of the table at the time of the match. Eleven took place at the stadium of the benefiting team. These ratios are not enough to conclude anything systematic, and I will not do so. But they are enough to raise a technical question: if VAR is a purely procedural mechanism, why does its distribution align so closely with the distribution of power in the league?

The answer may be very simple and very ordinary. Bigger teams control the ball more, attack more, put the ball into the opposition box more. The number of incidents requiring review is therefore higher. That is the most reasonable explanation, and I must state it before anyone reaches for another. But that reasonable explanation also means something: VAR does not level the playing field. It places a ruler on a playing field that was already tilted.

Three minutes and forty-seven seconds

Time is the second indicator I track, and it is far more honest than arguments about right and wrong. My average review time this season is two minutes and fifty-one seconds. Reviews exceeding four minutes account for roughly one fifth of all interventions, and they almost always fall into two categories: penalties and red cards.

A football match runs ninety-five to a hundred minutes of real time, but the ball is only actually in play for fifty-five to sixty of them. Every three-minute VAR review takes three minutes away from that in-play time, and takes away the rhythm a team spent twenty minutes building. For a team chasing a deficit and pushing its line high, those three minutes are dead time. For a team protecting a lead and absorbing pressure, those three minutes are a free interval.

I re-watched the footage of a round-eleven match this season in which the VAR team took four minutes and nineteen seconds to confirm a legitimate goal. During those four minutes, the trailing side lost its attacking momentum entirely. They did not score in the remaining eighteen minutes, despite having created five chances in the fifteen minutes before. I cannot prove causation. But I can record it, and keep recording it until the trend line speaks for itself.

The lesson of 2026

In 2026, at fifty-three, I was invited to commentate live on Vietnam against Cambodia in the Asian Cup qualifiers for a local Nha Trang television station. In the first half I misnamed the striker Nguyễn Văn Toàn three times, calling him Nguyễn Văn Quyết, even though the two play entirely different positions and have very different builds. Viewers called the switchboard to complain, and the editor had to message me through my earpiece.

After the match I requested the tape and sat through the full ninety minutes, writing down every mispronunciation and the tactical context that produced it. That naming mistake taught me that sport never forgives carelessness. Since then, every article and every podcast script carries a section I call name verification, with at least two cross-referenced sources by shirt number and position. The four-column notebook I hold in stand B is the child of that afternoon.

Workload: the variable that never appears on the scoreboard

The third indicator I track has nothing to do with referees, and I consider it more important. It is workload.

In a regular season a club plays twenty-six league matches across roughly eight months, plus the national cup. Counting travel, each club may make fifteen to eighteen away trips. For sides in continental competition, that adds six to eight more matches, usually midweek. Three and a half days between consecutive fixtures sits in what sports scientists call the danger zone: enough to accumulate fatigue, not enough to supercompensate.

I use a simple ratio anyone can calculate: acute workload divided by chronic workload, meaning this week's training and match volume over the four-week average. When that ratio exceeds one point five for two consecutive weeks, soft-tissue injury risk rises sharply across studies in multiple sports. I do not need a club's GPS vests to see it. I just count minutes.

This season I counted nine players across different clubs passing two thousand minutes after only fourteen rounds. That is a near-full-season load compressed into barely more than half the campaign. It is no surprise that the soft-tissue injury list — hamstrings, groins, calves — is markedly longer than at the same point last season.

Every injury crisis hides a recovery map, if you are patient enough to read it

In 2026 I worked as an assistant data analyst for the Toyota Nha Trang youth basketball academy. That June, the U16 squad's lead shooter, Trần Minh Hiếu, tore knee ligaments in a session before the national youth championship. The coaching staff wanted to shorten his recovery to make the registration deadline. I spent three nights rebuilding the recovery curves of twenty similar cases from 2026 to 2026, cross-referencing leg-press force data and knee flexion range week by week.

The result was something nobody wanted to hear: at least seven weeks before returning to high-intensity movement, and those seven weeks only held if force measurements on the injured leg reached ninety percent of the healthy leg by week six. I wrote a fourteen-page report citing precedents from the NBA and from domestic cases, and proposed a replacement from the youth pipeline. The academy accepted it. Hiếu sat out the tournament entirely, resumed full training in September, and returned the following season with an intact knee.

That story repeats almost verbatim at professional level, only at a larger scale and under heavier pressure. Whenever a club faces an injury to a key player, one group says he must play because the big match is coming, and another says he needs more time. The data always sides with the second group. But the data does not sit in the meeting room.

Major leagues learned this long ago. The NBA formalised load management from 2026, after studies showed soft-tissue injuries accounted for the bulk of games missed and the bulk of those occurred mid-season. They accepted the price of a star sitting out regular-season games to keep him for April. V.League has no such mechanism, and I am not sure it can, when every regular-season fixture carries ticket revenue, sponsorship obligations and a community waiting.

Young players pay the bill

What struck me most in my tracking this season was the share of under-23 players pushed into the starting eleven because of injuries rather than a development plan. I recorded seventeen cases of under-21 players starting a match they were not in the coaching staff's pre-season calculations for. More than half of them had never played more than two hundred professional minutes.

When a squad is short, it throws in young players. When a young player performs well twice, he no longer gets rest. When he breaks down in his seventh match, nobody remembers he is nineteen and has been playing elite football for four months. That loop exists across Southeast Asian football, and it is the most insidious form of exploitation, because nobody decides it. It simply happens.

The Toyota Nha Trang academy taught me this: a broken bone can heal, but broken trust needs an entire season to mend. A young player pushed too fast will heal his tendon, but he will carry fear into every duel, and that fear costs far more than the injury.

Pre-season money and the physical bill

This part is rarely discussed, but it belongs in the workload picture. In the four weeks before the opening round, most V.League clubs play friendly tours, partly for football reasons, partly to honour sponsor contracts. A team can play five friendlies in three weeks, travel to two or three provinces, with rest between matches insufficient to absorb the volume.

The science is clear: a season's physical base is built in the preparation phase, and it requires a controlled progressive load. A commercial friendly tour has no progressive load. It has an exhibition match, a signing ceremony, a late night, and a flight home. When the season starts and the team faces its third match in seven days, nobody goes back to ask what the July tour took away.

I am not arguing against clubs making money. Professional football runs on money. I only want those facts placed side by side on the same page, so supporters recognise that an injury in round five is not misfortune. It is the result of a chain of decisions that began in June.

When the national calendar and the club calendar collide

On 5 January 2026, Vietnam won the ASEAN Cup after victory in the second leg of the final at Thailand's Rajamangala Stadium. It was one of the rare peaks of Vietnamese football in two decades, and the joy was real. But from the analyst's chair I saw a consequence few discussed. Nguyễn Xuân Son suffered a serious injury in that very final, and a group of national team regulars entered club pre-season with almost no rest days.

Players are not machines with an on-off switch. After a demanding tournament lasting weeks, the body needs a genuine deload, not ten days followed by three sessions a day. In my notebook, players who entered pre-season with fewer than three full weeks of rest showed an absence rate from injury roughly one third higher over the first three months than the rest. This is a small sample, and I must say so plainly. But it points the same direction as everything I have read in exercise physiology, and that is why I write it down.

The counterintuitive angle: instruments have angles too

When I say VAR does not level the playing field, some people immediately hear a conspiracy theory. I want to stop that early, because conspiracy theory is the lazy form of analysis, and it ruins even correct observations.

Referees do not make calls on instructions from a secret room. Referees make calls based on what they hear, and in a stadium with forty thousand people, they hear a great deal. A single roar is enough to change a decision, because a referee's decision is a cognitive process unfolding in two seconds, under time pressure, from a line of sight that is half blocked. That is the structure of bias, and it needs no mastermind.

Where I disagree with the crowd is elsewhere. Supporters believe more VAR will make football fairer. I believe the opposite: more procedure means more points through which the weight of power can pass. Every review decision is a human choice, and human choices are made under the influence of context. In a big match there are more cameras, more angles, more public scrutiny. In a small match there are three or four angles, and a wrong decision goes unmentioned after two days.

There is one more variable I cannot ignore when analysing sports data in 2026. Positional and event data now flows in real time straight from stadiums to places that are not club analysis rooms. In those first seconds, the same data stream that helps a coaching staff understand a match also runs the betting markets on the other side of the world. I have no solution for this. I only record that when a match is fully digitised, it no longer belongs solely to the people playing it.

The breathing rhythm of endurance

In basketball, as in a pandemic, the only certainty is the breathing rhythm of endurance. In March 2026, when every competition was postponed indefinitely, my podcast Góc Nhìn Dữ Liệu had about three hundred listeners per episode. In the first two episodes after lockdown, audience dropped forty percent. Many colleagues switched to dressing-room gossip and gut-feel predictions, because that is easier to listen to. I kept the same structure: dissecting the zone defensive efficiency of VBA teams from the 2026–2026 season, publishing every Tuesday and Friday, missing nothing.

By June, a listener working as an assistant coach for the national team wrote to praise the accuracy, and from there I was invited to advise the coaching staff on data remotely. I tell this story to make one simple point: in a regular season, the winner is not the best team in one round, but the one that does not break in round twenty.

The variable for the next round

Three months will answer two questions the current data cannot reach. Whether the distribution of VAR decisions keeps tilting toward title contenders as table pressure rises over the final twelve rounds. And in parallel, whether clubs will dare rest a key player for one regular-season match, or whether they will keep loading him until his body decides on his behalf.

Three decades beside the pitch taught me this: endurance is not about never falling, it is about knowing how to fall correctly. For me, the most watchable thing in a regular season is not the league table. It is the fourth column in my notebook: the time the ball takes to roll again, and what was taken away while it waited.