Analytics is older than you think: (re)introducing Charles Reep

A blog by Sam Green from 2012 is often credited as kicking off the ‘expected goals era’ of football[1], but the first xG calculations are surprisingly older. As in, ‘almost as old as the Premier League’ older.

The adage that there’s nothing new under the sun probably holds true for this earlier work as well[2], but check out this diagram from a 1997 paper. Look familiar?

This ‘weighted shots’ work began with a mere observation that shots taken close to goal and central went in more often than shots from range, but the calculation grew from there. In the paper, ‘Measuring the Effectiveness of Player Strategies at Soccer’, a number of factors were considered in the further analysis: distance from goal; angle to goal; first-time shot or not; less than a yard to the nearest defender or not; shot from open play or a set play. As the caption above indicates, kicked shots were also separated from headers.

My friends, this is, in some ways, more sophisticated than some of the earliest xG models from the ‘expected goals era’ that would come a decade and a half later. The authors of the paper: Richard Pollard, and one Charles Reep.

Charles Reep has a history even muddier than expected goals. He was indisputably a pioneer of data collection, starting in 1950 with a pen and a notepad (and sometimes, at night games, a miner’s helmet). He worked with Brentford and then Stan Cullis’ Wolves in the 50s, a decade in which the Midlands side won three league titles.

But Reep’s loudspoken articles in the 1960s, principally in World Sports magazine, looked like he was misinterpreting his own data. They highlighted how many goals were scored from short sequences of possession, but implied that this made short sequences more effective without noting that short sequences were primarily just more common.

Since then, his name has become associated with what happens when data analysis can go badly.

The work of Reep’s career in totality is fascinating though, and his position within the English game says something not just about it but about us. We’ll get to that 1997 paper again soon, but let’s take a brief step back to where it all began.

Reep is often referred to as an RAF veteran, usually with his rank of Wing Commander, but he was an accountant by trade before joining the military. That does make all of this data-recording make a bit more sense, the accountant airman.

He was inspired by a talk given by then-Arsenal captain Charlie Jones in 1933 about Herbert Chapman’s tactics, but it was 1950 that he first started creating data. This being the mid-twentieth century, Reep had to physically be at the games to do this, although was later able to record data from major matches via the magic of television.

This physical necessity, and the ‘completeness’ of the collecting, are unlike modern collection practices of course. A 1968 paper[3] which uses some of the data gives an insight into its limited breadth — 12 Wolves games from the 1953/54 season; 15 miscellaneous games in 55/56; two full seasons of Sheffield Wednesday (while working for them); 18 miscellaneous games… It goes on like this through the whole 1953-1967 period.

It’s slightly difficult to know exactly who, in the professional game, Reep worked with during his life. He definitely did work for Brentford, Wolves, and was full-time with Sheffield Wednesday for three seasons after retiring from the RAF.[4] He met Graham Taylor several times, rather than a more formal collaboration, but has been erroneously attributed as working with Cambridge United, Sheffield United, and Wimbledon.[5]

So while Reep wasn’t a string-pulling svengali of Ye Olde English long-ball football, his public writings perhaps made it easy to think he was (several people who were inspired by him did work more extensively in football too, but more on that in a moment).

While in the 21st century the ‘analytics community’ was more aligned with possession-based football, Reep was anything but. Thanks to a 2018 Duncan Alexander tweet, we can read one of Reep’s World Sport articles in full (Alexander bought the magazine as part of writing his 2017 book Outside the Box).

“Reflection upon the significance of all this,” Reep wrote in 1962, referring to his data, which was reproduced in a table in the magazine, “must cause one to question many tactics now widely praised as ‘good football’.” The article ends in a series of questions, culminating in this:

Have British observers been deceived for years by too readily accepting the assurances that “Continental style” football is superior to the English direct style (as it was before 1953*) and therefore has to be imitated?

Statistics prove the answer to all these questions is definitely YES.

* [I think by ‘as it was before 1953’ Reep is referring to the English style prior to that date]

Over 40 years later, Reep’s analysis was critiqued by two foundational books for the modern analytics ‘movement’, David Sally and Chris Anderson’s The Numbers Game, and Jonathan Wilson’s Inverting the Pyramid. The latter book gives the most straightforward and succinct summary of the problems with what Reep’s analysis appeared to be:

If, as [Reep’s] figures suggest, roughly 80 percent of goals result from moves of three receved passes or fewer, but 91.5 percent of moves consist of three received passes or fewer, then it surely follows — even within the unsubtle parameters Reep sets out — that moves of three passes or fewer are less effective than those of four or more.[6]

However, recent years have seen Reep’s influence on English football massively overstated. Christoph Biermann’s 2019 book Football Hackers, says “[i]n England, Charles Reep’s long-ball dogma influenced the game for a number of years even though it was based on wrongful interpretations of the data.”[7] One 2016 FiveThirtyEight article ran the title ‘How One Man’s Bad Math Helped Ruin Decades Of English Soccer’. There’s a danger that we slip into thinking that Reep is responsible for England’s long-ball history and tactical insularity.

His analysis was faulty, but any institutional ruination of English football doesn’t lie with the accountant airman. There’s an argument that we could blame Charles Hughes, who was inspired by/ripped off Reep’s work (depending whether you asked Hughes or Reep) and was the FA’s director of education and coaching between 1983 and 1994.[8] It seems likely he had an influence, but (particularly given that I’m affording a nuanced take of Reep here) it seems a stretch to lump all the blame on Hughes.

This is partly because, importantly, it’s clear from Reep’s own experiences that he wasn’t alone in his beliefs on the game.

The previous quote from his World Sport article, about ‘Continental possession football’, could have been written at any point from then, in 1962, to now, in 2021. Back in the 1950s, Wolves manager Stan Cullis already believed in the long-ball approach that Reep waved a spreadsheet at to back up. Reep surely approached Graham Taylor in 1980 for the same reason. Presumably he recognised a kindred spirit (who might listen to a man trying to introduce statistics into football) and figured that might be a rare opening to work in the game that so clearly fascinated him.

England has always been welcome to the type of football that this pioneer of analytics was proposing. However, we should note that it’s not like English football ever totally succumbed to it. In 1983, an article in The Times which was Graham Taylor’s Watford, as well as the Charleses Hughes and Reep, notes:

There were not a few insults inside the Cottage [Craven Cottage], directed from Fulham’s supporters among a 22,000 crowd at Watford’s tactics, which are persistently breaking with currently accepted thinking, weathering the criticism from such as Keith Burkinshaw [Tottenham manager] and Malcolm Macdonald [Fulham manager] and doing very nicely, thank you.

The article later introduces Charles Hughes with the sub-clause “whose theory turns what is supposed to be the fundamental principle of Liverpool’s success, possession football, on its head.” At the time that the journalist, David Miller, was writing, Liverpool were on course to win their sixth league title in eight years, a period of time that had seen them win three European Cups already. A fourth would come in 1983/84.

English football, therefore, knew the success that a more possession-oriented style could bring. It’s not as if any of the ‘successful’ long-ball teams, such as Wimbledon (who beat Liverpool in the 1988 FA Cup final) who popular either. England didn’t embrace them as a proud embodiment of the nation’s footballing philosophy.

So no, Charles Reep didn’t ruin English football. And so we enter the second half of his career — the co-author of academic papers — and approach the groundbreaking work we saw earlier.

If it’s hard to know who Reep worked with in the professional game, it’s not exactly easy to know what work he did on the papers either. The first appeared in 1968, then another in 1971, and some more in the intervening years until the one this post opened with in 1997.

Those two early papers are tables of data more than anything. From a modern viewpoint they look quaint, but — given that both are now half a century old — they’re absolutely foundational.

The first (Reep partnering with Bernard Benjamin[9]) is primarily a presentation of Reep’s data around length of passing moves and which passing moves led to shots. Pass moves got less and less frequent with each added pass; goals from moves starting in the final quarter of the field accounted for 50+% of all goals; things like that.

The 1971 paper (with Benjamin and Richard Pollard) was more academically mathematical in output, noting that the distribution of passing move lengths (1 pass, 2 passes, 3 passes, etc) seemed to have a ‘negative binomial’ pattern. The pattern isn’t really important in itself, but it’s statistical knowledge about football being committed to the record, and that is important.[10]

The culmination, in 1997 (when Reep was 93), wasn’t merely a precursor to expected goals. From his early days analysing the game, our accountant airman had noted that obtaining possession of the ball in different areas of the pitch had a big impact on chances of scoring. The 1997 paper expanded on this, introducing a (very) rudimentary kind of expected possession value system, based on where a sequences of play began. Pollard and Reep called it the ‘yield’ of possessions.

Here’s an excerpt from the paper: “In terms of probability, the yield of a team possession is the estimated probability of scoring a goal minus the estimated probability of conceding a goal, based on the outcome of a possession.” A yield of 0.025, they write, would mean that 1000 possessions starting in that particular zone would lead to 25 more goals scored than conceded.

The paper even included some analysis of different tactical approaches for different types of possession:

[Image seems to have been lost when transferring website providers]

The sample sizes are, perhaps, quite small but consider that this is 1997. This was over a decade before something as simple as possession percentage became a statistic of discussion in the public realm. A number of the people reading this newsletter will not have even been born when this was written.

Why didn’t it have more of an immediate impact? Possibly availability of the paper; possibly availability of large datasets to the people who were likely to have read it. One of the main takeaways I have from reading this work — and other early analytics research — is that a lot of the ideas existed before, but the data and technology to allow the exploration of that idea might not have. History usually takes its course on the technology side, and professional data collecting operations sprung up too.

However, there’s another takeaway I get from the story of Charles Reep that can have a more immediate impact regardless of where history is: the significance of collaboration.

I’m currently reading The Innovators by Walter Isaacson; the book is subtitled ‘How a group of hackers, geniuses and geeks created the digital revolution’ but Isaacson has a deeper motive than just history-telling. In the book’s introduction he writes:

This is the story of these pioneers, hackers, inventors, and entrepreneurs — who they were, how their minds worked, and what made them so creative. It’s also a narrative of how they collaborated and why their ability to work as teams made them even more creative.

The tale of their teamwork is important because we don’t often focus on how central that skill is to innovation. There are thousands of books celebrating people we biographers portray, or mythologise, as lone inventors[…] But we have far fewer tales of collaborative creativity, which is actually more important in understanding how today’s technology revolution was fashioned.

I think the same may be true of Charles Reep.

While his sometime co-author Richard Pollard fiercely defends Reep in a 2019 paper[11], the former accountant/Wing Commander didn’t do himself any favours in his early ‘60s articles. The papers co-authored with Benjamin and then Pollard contain much more focus, and much more considered insight. Reep may well have brought some of this himself[12] but it seems reasonable to say that his co-authors also brought something to the table (Bernard Benjamin became president of the Royal Statistical Society in 1971; Richard Pollard completed a PhD in statistics applied to football analysis in the 80s).

From the time I entered into the football analytics sphere around 2013, little groups of people have always been around advances. The StatsBomb blog brought a lot of people together either to write or at least to read under one roof. Companies like Opta and Prozone/STATS (now jointly Stats Perform), Hudl, 21st Club (now Twenty First Group), Decision Technology (and others I’ve probably missed) had groups of people working on problems. American Soccer Analysis is probably the best current, public example of collaboration feeding creativity and analysis.

Individuals may produce good work on their own, but it tends to be when they gravitate to discuss their ideas with others that these get refined and improved, made applicable to the game or pushed even further.

Charles Reep was a pioneer of performance analysis and a driven, methodical individual. But while driven and methodical individuals can do good work on their own, it’s usually when they have someone to bounce their ideas off that it becomes great work. A 1997 paper containing rudimentary expected goals and expected possession value calculations…?

That’s great work.