The fourth book I completed in 2025 was xGenius by James Tippett. This is Tippett’s second book about the application of data analytics to football – I read his first, The Expected Goals Philosophy, back in May 2022. xGenius follows up TEGP by digging deeper into the mathematical basis of a range of football statistics such as Expected Goals (xG), and the history of how these measures were developed by professional gamblers looking to get a edge over traditional bookmakers. It turns out that those gamblers were so successful that they pocketed large enough fortunes to become owners of football clubs (e.g. Brentford, Brighton and Hove Albion) and then proceeded to transform those clubs by basing all decisions about things such as player transfers and on-field tactics on those same statistical measures.
I found it interesting to read some more detail about the individual statistics and the various ways that they can be applied, but the most interesting parts of the book were when Tippett highlighted how the way that football is now being played has been transformed by coaches adjusting their tactics to reflect what the data/statistics reveal to be the most effective strategies, despite these often being counter-intuitive. For example, data analysis shows that the chances of scoring a goal from a shot taken from outside the penalty area is very low (around 2%), and so even when an opportunity to shoot from distance presents itself it is arguably better not to shoot but to try to work the ball into the golden zone within the central part of the penalty area – i.e. to take less shots but ones with a higher probability of being goal-scoring ones. Shoot less to score more! Similarly, goals from aerial crosses are rare, as are headed goals and goals scored direct from corners. So, the modern trend of the top teams to focus on retaining possession with lots of ‘tippy-tappy’ passes, whilst trying to get the ball into the perfect spot for a high-probability shot, is rooted in the message that comes out of data analytics, as is the preference for taking short corners rather than launching the ball straight into the box in the hope that a big striker will get his head onto the cross.
A lot of what I don’t particularly like about the way that many of the very ‘best’ teams now play, which I think can make a game really quite boring, can be blamed on the attention now paid to data analytics. This makes sense I think. If data analytics show that a certain approach to games is the most efficient way to win games, then the teams that adopt that approach best become ruthlessly efficient winning machines, and much of the drama in the game, aka the uncertainty, falls away. But I think there is some hope, because surely as more and more teams adopt the same, supposedly most effective tactics, there is increased scope for a team playing differently to surprise their opponents and gain an advantage in the process. It wouldn’t surprise me at all if, after a decade or so in which possession-based football, leading to opportunities to create near-perfect, almost unmissable, chances to score, more teams start to return to a more direct, and potentially more exciting, approach to the game.
One other thing that was very much on my mind while reading xGenius was that the whole field of sports data analytics has emerged in the last 10-15 years. At the time when I was thinking about what I would do with my life back in the early/mid-1980s, the idea that it would be possible to be a professional data analyst for a football team would have seemed laughable. I can’t help thinking that as a scientifically-minded and mathematically-capable teenager who was somewhat obsessed with football scores, facts and figures, if such a career avenue had been possible I would have been all over it. Patterns, trends, maths, numbers, tactics, strategy and football? What’s not to like!
Tim O'Hare 