Wind, Carbon Shoes and Races Without Splits

Late June, on the straight of a provincial stadium, an internal testing group called out a number: 10.42 seconds over 100 metres. The stands were empty. No crowd, no media, just two coaches, a phone filming, and a sheet of paper. I sat in the third row, opened my notebook, and the first question I wrote down was not how fast he ran. It was how strong the wind was.

The sheet had no field for that.

For the rest of the week, 10.42 came back in at least four conversations I sat in on. It appeared in a coaching group chat. It was written beside the name of a nineteen-year-old. It was used to justify a funding increase. Nobody asked about wind velocity. Nobody asked whether the watch was hand-held or electronic. Nobody asked which repetition of the session it was, on what surface, at what point in the training cycle.

A blank data sheet is never neutral. It is a gap, and gaps get filled with whatever people already want to believe.

Vietnam's athletics transfer season has no private jets and no hotel meeting rooms. It runs quieter: a department conference room, a training centre payroll, phone calls between one delegation's head coach and another's administrator. The mechanism is not far from football's. After every Games cycle, units review their rosters, keep, release, borrow. The managing unit pays for food, housing, medical care, equipment. The athlete pays back in medals, and medals convert into administrative performance targets for an entire system behind them.

Inside that loop, everyone needs a number to present. A coach needs a number to defend an investment slot. A delegation official needs a number to defend a quota. A parent needs a number to decide whether a child should pursue the sport at all. Nobody in that room wants to hear about a blank field.

Vietnam's athletics data is not as poor as outsiders assume. National championships use electronic timing and wind gauges, keep official records and archive them. The problem sits elsewhere: most of the numbers used to make decisions do not come from there. They come from internal testing sessions, from trial runs, from notes passed by word of mouth between coaches. That is data without conditions attached, and data without conditions cannot be verified.

I keep a five-layer filter for every track and field mark that crosses my desk. It is not complicated. It only requires three extra minutes of asking.

Layer one: wind.

In the 100 metres, 200 metres, 100m hurdles, 110m hurdles, long jump and triple jump, World Athletics ratifies a record only when the assisting wind does not exceed 2.0 metres per second. That rule exists for a very concrete reason: wind can hand an athlete more than several months of training. Usain Bolt ran 9.58 seconds in Berlin on 16 August 2026 with a wind of +0.9 metres per second. Three days later, on the same track, he ran 200 metres in 19.19 seconds with a headwind of -0.3. Both are world records, and both are recorded with their conditions.

At provincial testing sessions, wind gauges are often absent. The rule of thumb analysts use is that each 1.0 metre per second of assisting wind is worth roughly 0.05 to 0.06 seconds over 100 metres. A 10.42 run in a +2.3 metre per second tailwind, once adjusted, lands around 10.55 to 10.60 in still air. That difference is enough to reorder a proposal list entirely.

Layer two: the equipment dividend.

Since 2026, World Athletics has tightened footwear rules. Road racing shoes are capped at a 40-millimetre stack height with a single rigid plate. Track spikes are capped at 20 millimetres for events up to 400 metres hurdles and 25 millimetres for 800 metres and above. Those limits were not written to suppress technology. They were written to keep a performance partly measurable as human capacity.

The clearest example sits in the marathon. On 12 October 2026, Eliud Kipchoge ran 1:59:40 in Vienna. That was not an official record and was never ratified, because the conditions were engineered: rotating pacemakers in formation, wind shields, a scripted attempt. His official record is 2:01:39, set in Berlin on 16 September 2026. Nearly two minutes separate two runs by the same man, and that gap says a great deal about how much the environment contributes to a number.

At school, university and internal testing level, the equipment variable is almost never recorded. An athlete switches to a stiffer carbon-plated shoe, improves by 0.3 seconds, and the room concludes he has progressed. Perhaps he has. But if most of the gain came from the sole, the coaching staff is pricing a shoe rather than a person.

Layer three: small samples.

One race is not a level. It is a single data point, and single data points in sport carry a lot of noise. My method is to take at least eight to ten competitive runs across twelve months, sort them, and look at the median rather than the best value. The median is what you can buy. The best value is what you can sell.

In transfer season, the most common pricing error is treating an athlete's peak as the athlete's price. One good run on an afternoon of favourable wind gets written into a file as a stable capability, and three months later people sit in a meeting wondering why the result never repeated. The answer is usually already in the older data. Nobody bothered to arrange it into a series.

Layer four: unratified training marks.

Athletics has an old and stable conversion convention. When comparing hand-timed results with electronically timed ones, you add roughly 0.24 seconds for 100 metres and roughly 0.14 seconds for 200 and 400 metres. The reason is the reaction delay of the person pressing the watch and the actual instant the athlete crosses the line.

A hand-timed 10.42, once you add 0.24, becomes 10.66 on an electronic clock. If that session also had a tailwind, the real figure sits somewhere near 10.90. A 10.4 potential in a meeting becomes, after two corrections, a young athlete running around 10.9. Nobody lied. The sheet was missing two fields.

There is another layer few notice: a mark produced in a training session after full recovery, in a single effort, is not the same kind of mark as one produced in the third round of a championship. The body is in two different states. An athlete's transfer value lies in repeatability under unfavourable conditions, not in the best run under ideal ones.

Layer five: split data.

This is the most important layer and the least recorded. A 10.42 hundred metres can be split into two entirely different athletes. The first type runs the opening 60 metres in 6.5 seconds and the closing 40 in 3.92. The second runs the opening 60 in 6.7 and the closing 40 in 3.72. Same final number. Two different products.

The first is a strong starter, suited to relay legs, where 100 metres is divided into four segments and the opening segment decides a great deal. The second is a finisher, suited to the 200 metres, where the second half of the race is where things are settled. Buy the first to run the 200, or the second to run an opening relay leg, and you have paid for a capability you will not use.

Without split data, you are not buying an athlete. You are buying a number, at the price of belief.

Here I have to go back. In 2026, while working as a data consultant for a football club in Hải Phòng, I identified a young midfielder with an average PPDA of 6.8, the best in the academy system, meaning he pressed better than anyone in his age group. He had been overlooked because of his modest build. I brought the table into the meeting room and asked for him to be given a chance. Against Hà Nội FC he recovered the ball 14 times, provided one assist, and the team won 2-1.

The decisive metric in that story was not on the standard statistics sheet anyone could read. It sat in a column nobody had built yet. Hải Phòng taught me this: the star is not on the shirt, it is in the indicator.

In athletics, the decisive blank sits in the same kind of place. Wind velocity, timing method, split data, sole thickness, number of prior repetitions in the session. Five fields. None of them requires expensive equipment to record. They require someone willing to sit down for three more minutes after the session ends.

There are two things I have to say against myself.

First: a clean correlation is not a cause. When I compiled five seasons of data during the football shutdown, I gathered 2,300 matches and found that the group of teams with a pressure index below 8.5 averaged 1.8 points per match, well above the rest. That figure is correct, but it does not mean pressing generates points. It is entirely possible that good pressing teams are simply better funded teams with deeper squads, and that those two things generate the points. I had to rewrite the conclusion of that model twice for exactly that reason.

Second: not enough data to conclude is a legitimate professional answer, and the market punishes anyone who gives it. In transfer season, a consultant who returns a blank field is read as a consultant who cannot do the job. So people invent. In 2026 I put a set of splits into a report, then discovered the source was a testing session with no wind gauge, hand timing and no recorded order of repetitions. I pulled it from the report and set a rule for myself: every number entering a report carries the conditions that produced it, or it does not enter.

Data is a mirror. Most of the market looks into it and sees only itself. People search a table for confirmation of what they already believe, and when the table is blank, they write it in themselves.

A season is a confession of tactics. A transfer window is a confession of evaluation method.

Over the next six months I will track three things. How many internal testing sessions record wind velocity. How many provincial meets switch from hand timing to electronic. And how often training marks appear in proposal files without conditions attached. If none of the three moves, the price of every medal in the next cycle will keep being set by belief.

The ball rolls in one direction, but data can see in all of them. The problem is you need data first.

The question I left with the coaching staff that afternoon: if you delete the empty wind field, are you buying a 10.42 athlete, or are you buying a gust of wind?