How Liverpool FC used big data to gain an edge

After taking over Liverpool FC, Fenway Sports Group used the example of American sports and big data insights to give the football club a strategic advantage, impacting tactics and recruitment.

In this extract from his new book, Data Game: The Story of Liverpool FC's Analytics Revolution, Josh Williams explores how this marriage of data and football began and how, over the course of around a decade, Liverpool FC became an industry leader in data science. 

In 2019, RunRepeat conducted a study surrounding the presence of bias in football. The Danish research firm analysed 2,073 statements from commentators in 80 football matches, discussing 643 unique players of various races and skin tones. Their findings suggested that, when talking about intelligence, 62.6 per cent of praise was directed at players with lighter skin, whereas 63.3 per cent of criticism was aimed at those with darker skin. When speaking about power, commentators were around 6.6 times more likely to be talking about players with darker skin tones. When talking about work ethic, 60.4 per cent of praise was aimed at players with lighter skin tones.

Whether it’s conscious or unconscious, players are often judged and evaluated because of irrelevancies. Too much attention tends to be given to details that simply don’t matter. If a football player decides to wear gloves on the pitch, they can be sure that some spectators, including scouts, will derive conclusions about elements of their character. A male player’s hairstyle can impact how he’s perceived, and the same goes for whether a player is inclined to shout at their teammates or not. From a player’s nationality to the colour of their football boots to the number of cars in the garage to whether or not they watch football in their spare time, opinions are forever being shaped. The infamous and perhaps exaggerated recruitment scene in Moneyball involves scouts coming to conclusions about a baseball player because of the shape of his jawline and the appearance of his girlfriend. Some elements matter, others certainly do not.

"The players I really like are those who shine through in the data, but don’t naturally shine through for your typical football fan or scout," he said. "Awkward, ungainly players, or players who have been overlooked, for various other purposes". Naby Keïta was one of [Liverpool FC Director of Research from 2012-23] Ian Graham’s leading lights. He was an analytics darling who portrayed himself as a restless, all-action midfielder in the numbers.

Keïta was always best loved by those who consulted data before forming their opinions. All was going according to plan before Keïta picked up his first setback at Liverpool just eight matches into his first Premier League campaign. His next came in March, followed by another in May. Keïta was injured for the start of the following season, and with Trent Alexander-Arnold and Andy Robertson quietly establishing themselves as full-back creators who rarely missed a single minute of action, Klopp’s blueprint for the development of his team was cautiously changing.

With Liverpool’s playmaking full-back duo growing in prominence, the need for an expressive and audacious midfielder like Keïta was lessening. Klopp suddenly required little more than a safety net in the middle of the park, with Henderson thriving as a functional presence who simply did a job for the team alongside Gini Wijnaldum and Fabinho. Keïta was almost tasked with playing within himself whenever he was free from injuries and presented with game time.

Robertson was once earmarked by Graham as another one of his gems. The Scottish left-back moved to Anfield around five weeks before Liverpool struck a deal with Keïta’s representatives, costing as little as £8m. He was a proper Moneyball signing. Just 23 years old at the time, Robertson was contracted to Hull City, who struggled at the foot of the Premier League. He formed part of a dysfunctional outfit and, because of their failure to compete, Robertson spent most of his time defending and was rarely allowed to venture into the final third. Nevertheless, Liverpool recognised his offensive qualities and believed he would prosper in a different and more favourable environment.

"One of my favourite players is Robertson, our left-back, one of the best left-backs in Europe, and now a European champion of course," Graham later said. "His problem was his background as much as anything. He only started playing Premier League football around the age of 22. He was the best young full-back in Britain at the time. He was a strange case of a really attacking full-back playing in a really poor defensive team".

Peter Moore, who was CEO from 2017 until 2020, was a speaker at the World Football Summit in 2019. The Liverpool-born business executive offered an insight into the inner workings of the club in his talk.

"We look at data. There’s a merging of that data with experienced eyes, so the analogue and the digital come together, and a lot of that legacy is the belief that John Henry, Tom Werner and Mike Gordon have in owning the Boston Red Sox. They hadn’t won the World Series for 86 years, but applied science and technology to analysing players and understanding what players need for the Red Sox to create the best chance to win. It is that combination of an experienced eye looking at an athlete combined with data, combined with psychological outputs. We have a sporting director who is akin to a general manager in American sports. He and our scouting staff and analytical staff are the ones who build the squad. Jürgen Klopp as the manager gets the best out of that squad. Together we come together as an entity".

Mohamed Salah is perhaps the most obvious of Liverpool’s data-fuelled transfers. Julian Brandt was reported as the man that Klopp wanted. The Bayer Leverkusen prospect was showing signs of becoming a star in his homeland, but Edwards and Graham had other ideas. Salah, according to their analysis, was the man to get. "He will score goals, trust us," was the message to Klopp. He was regarded as a Premier League flop because of his failed spell at Stamford Bridge, but the label was unfair. "Salah didn’t fail at Chelsea," said Graham. "He failed to get on the pitch".

You didn’t need a PhD to recognise that Salah was an output merchant. His basic offensive numbers were enough to grab the attention of even the most amateur analyst. The list of records broken by the Egyptian captain after he returned to English shores is almost endless. Of all of the players signed by Liverpool during the FSG era, nobody endorsed their scientific approach more appropriately than the guy who seemed to accumulate numbers in his sleep.