The first xG table I wrote by hand: A data monk's 7-year journey in V.League

I still remember the heat of March 2026, sitting on a bus from Vinh back to Saigon, one hand holding my old laptop, the other hand recording every single shot from SLNA into a self-made Excel spreadsheet. Back then, nobody in Vietnam called it data. They called me crazy.

The first xG table I wrote by hand on a bus ride, when nobody called it data yet. But I knew I was seeing something the rest of Vietnamese football hadn't noticed.

Seven years later, sitting at my usual coffee shop on Nguyen Dinh Chieu Street, staring at 14 xG charts of the entire V.League 2026 season, I still keep that habit: writing down the first numbers by hand before running any model. Some say I'm outdated. I tell them: data doesn't need security, it needs honesty. And honesty starts with verifying every number yourself.

The journey from zero to the first model

2026 was a landmark year for Vietnamese football. The U23 team had just made history in Changzhou, but V.League was still a mess of rushed foreign signings and rough tactics from local coaches. When Thames, the first sports data company in Vietnam, was just starting out, I built my own xG model for all 14 V.League clubs.

I collected data from VTV broadcast tapes, from sports newspapers I bought at street stalls. Every shot was recorded by hand: shot location, angle, type of chance, number of defenders between the ball and the goal. I had no Opta, no Wyscout, no modern tools. I had my eyes, a notebook, and the patience of someone who has lived with football for 28 years.

The result of the first 6 months was a database of over 3,000 coded shots. When I looked at the numbers, something strange appeared: Phan Van Duc – a 20-year-old winger from SLNA – had an xG per game of 0.48, higher than foreign stars like Patiyo from Hai Phong or Stevens from Binh Duong. Although Duc only scored 5 actual goals that season, my model said he should have had 9-10 if luck had been on his side.

I wrote a prediction: "Phan Van Duc will become a national team mainstay within 3 years." The article was mocked on football forums. A colleague called me: "Are you crazy? He only scored 5 goals and you say he's better than foreigners?"

I didn't argue. I just said: "Wait."

In 2026, Phan Van Duc scored the decisive goal in the AFF Cup final, securing Vietnam's championship after 10 years of waiting. I didn't jump up to celebrate. I just opened my old xG table, looked at the number 0.48, and smiled.

The xG table on the bus and the lesson of humility

The Phan Van Duc story wasn't my victory. It was the victory of methodology. But it also taught me an important lesson: models are never absolutely right, they're just less wrong than intuition.

My first handwritten xG table was full of errors. I measured shot angles by eye, not by machine. I didn't distinguish between strong and weak foot. I ignored weather conditions, pitch quality, and – most importantly – the psychological pressure from the stands. These were variables my model couldn't measure, and I always dedicate a paragraph in every article to acknowledge that.

"My model doesn't cry, doesn't celebrate, but after every match it owes me a lesson." That's what I often tell students when I lecture on sports data analysis.

In 2026, I decided to upgrade my model. I partnered with a software engineering team to build an algorithm that automatically recognizes shots from video. We failed 7 times before the first test run. But every failure reminded me of those sleepless nights on the bus, and I told myself: "At least now you have a computer. Back then you only had a pen."

World Cup 2026: Croatia and the birth of a brand

In June 2026, I went to Russia as a sports journalist. But I didn't write like a journalist. I brought my PPDA (Pressing Adjusted) model, developed earlier that year, and started measuring every team with that metric.

When Croatia faced Argentina in the group stage, I sat in the press room at Nizhny Novgorod Stadium, looked at the data, and couldn't believe my eyes. Croatia had a PPDA of just 7.9 – meaning they allowed Argentina an average of 7.9 passes before intervening. That number was lower than Spain, the team known as the masters of possession. But what caught my attention wasn't the PPDA number, but how Croatia pressed: they didn't press across the whole field, they pressed selectively, focusing on Argentina's weak defense with a 40% duel success rate.

I wrote a long article: "Croatia will reach the 2026 World Cup final." Colleagues laughed at me. "Croatia? A nation of 4 million? You're crazy."

"The world sees Croatia as underdogs, I see them as a sequence of coefficients nobody dares to exploit," I replied.

When Croatia successively beat Argentina, Russia, England and reached the final, my article went viral on social media. A major European sports newspaper even interviewed me about the PPDA method. I told them: "I'm just a guy who wrote xG tables by hand on a bus from Saigon. Don't ask me about tactics, ask me about data."

Pandemic 2026: Empty stadiums but data remained

In March 2026, COVID-19 swept the globe. V.League was suspended indefinitely. Major European leagues also shut down. Many sports journalists switched to writing about game shows, about players playing FIFA online, about anything that could keep readers engaged.

I didn't. I locked myself in my study, opened the V.League database from 2026 to 2026, and began a long-term study. 6 months, 10 seasons, over 1,500 matches, and hundreds of thousands of shots re-analyzed.

The result was a shocking discovery: clubs that changed their chairman mid-season saw their win rate drop by 23% in the next 5 matches. The cause? Management disruption. A new chairman usually brings a new coach, or at least a new tactical direction. Players need 3-4 weeks to adapt, and during that time, results plummet.

I published a 5-part retrospective series: "Management and Football: When the Chairman Leaves, What Does the Club Lose?" Each part analyzed a specific chairman transfer: from Ha Noi FC to SHB Da Nang, from Becamex Binh Duong to Saigon FC. I showed that changing a chairman isn't just an administrative matter – it directly affects tactics on the pitch.

After the article was published, a club CEO called to thank me. He said: "Your article helped us avoid sacking our head coach at a sensitive time." I asked him: "Why didn't you read my article earlier?" He laughed: "Because back then I thought you were just a crazy guy with an xG table."

Lessons from 7 years of data

Seven years after I first wrote an xG table on a bus, I've changed a lot. I'm no longer a dreamer with an Excel spreadsheet. I've built an analysis team, have access to Opta and Wyscout data, and my articles are read by hundreds of thousands of people every month.

But I still keep the habit of writing down the first numbers by hand. Every time I start a new project, I take out my notebook, write the first numbers with a ballpoint pen. That's how I verify the honesty of the data, before letting the computer process the rest.

"Fans see the play, I see 22 numbers moving — and patiently wait for them to tell a different story."

I don't trust coaches, I trust models. But I listen to coaches to fix the model. That's my philosophy. Models are never perfect, but they're always honest. And honesty, in a world full of emotions, is the most valuable asset a data journalist can possess.

The future of Vietnamese football data

V.League 2026 is entering its decisive phase. Clubs have invested heavily in foreign players, but data shows that the quality of foreign players this year is 15% lower than the 2026 season. I warned about this at the start of the season, and so far, 60% of V.League goals still come from local players.

"The transfer market is a game for those who see far, not those who see much — value always comes after patience."

Vietnamese clubs still chase names instead of data. They sign foreign players who scored in the Thai second division or the Brazilian third division, without checking whether they fit the team's tactical system. The result is that half of the foreign players have their contracts terminated before the season ends.

I proposed a project: build a foreign player database for V.League, with xG, xA, PPDA, and conversion rate metrics. I want to help clubs make decisions based on data, not based on YouTube highlight reels.

But the project is still on paper. The reason? "In Vietnam, football is emotion, not numbers," a club director told me.

I don't disagree. I just say: "Emotion fills the stands, but data wins championships."

And I will keep writing, keep analyzing, keep sitting on those buses with my notebook and pen. Because I know, one day, someone will read my article and realize: data is not the enemy of emotion. It's the most honest companion football has ever had.

"My model isn't wrong, it just needs an update."