Is strength of schedule a strong argument against a frozen table?

By Andrew Puopolo, @andrew_puopolo

While it pales in comparison to the many societal, economic and public health challenges posed by the ongoing COVID-19 epidemic, the football world is grappling with the challenge of determining a suitable and equitable way for completing the remainder of their seasons. UEFA have recently published guidelines stating that "if a domestic competition is prematurely terminated for legitimate reasons" the procedure adopted by a National Association for selecting clubs for participation in 20/21 UEFA tournaments should be "based on objective, transparent and non-discriminatory principles". Although there is still talk of playing out competitions behind closed doors, some leagues, most notably in Belgium and Scotland, have decided to end the season by ‘freezing in place’ such that the current standings become the final standings, the leaders become Champions, and the teams in the relegation zone go down.

This method for settling the end…

Using Data to Analyse Team Formations

I recently presented a research paper at the FC Barcelona Sports Analytics Summit on detecting and analysing team formations using tracking data (click here and scroll down to find the paper). I thought it would be nice to publish a shorter version on my blog. The work, which was awarded the "best research paper" prize at the conference, was done in collaboration with Mark Glickman at the Harvard Sports Analytics Lab.

Too long? You can take a look at the poster version here, or the cartoon version here.

A vital aspect of a football manager’s job is to select team formations – the spatial configuration of the players on the field. The choice of formation determines player roles, how they interact, and influences the playing style of both teams during a match. Despite their central role in team strategy, descriptions of formations are largely reliant on classifications based on the number of defenders, midfielders and forwards: crude summaries of player configurati…

From Sessegnon to Sanchez: How to calculate the correct market salary for EPL players.

In the 2018 January transfer window, Manchester United signed Alexis Sanchez on a four-and-a-half year contract. He had just turned 29, which is towards the end of the peak years for an elite forward. Yet Ed Woodward made him the highest paid player in the country, offering him a reported £350,000 per week, which equates to £18.2 million per year, or £82 million over the duration of the contract (before bonuses and signing-on fee).

United have undoubtedly received a spectacularly poor return on their acquisition. Granted, Sanchez has had his fair share of injuries, but it is clear that United chose to massively overpay a player whose abilities were likely to decline. Putting their recruitment issues aside (for now), what would have been a more reasonable salary for an EPL player of Sanchez's age and calibre? What should Woodward have offered him?

Market value salaries
We can attempt to answer this question by combining two very useful datasets: the estimate of th…

Liverpool have never been so dependent on United avoiding defeat

The Manchester derby on Wednesday will go a long way towards determining the outcome of the English Premier League title race this season. Liverpool are two points ahead of Manchester City, having played a game more. After Wednesday, both teams have three matches remaining: Liverpool play relegated Huddersfield at home, then Newcastle away (who are now safe from relegation), ending the season by hosting Wolves at Anfield; City play Burnley away, Leicester at home and then Brighton away.

City are expected to win their last three matches, so Liverpool fans will be desperate for United to avoid defeat in the derby, which would leave Liverpool with at least a one-point lead going into the final three matches. FiveThirtyEight's model indicates that Liverpool currently have a 43% chance of winning their first English title in 29 years. If United win the derby, this increases to around 74%, or 69% if the game ends in a draw. However, if City win, Liverpool's title chances drop to 3…

Do we overestimate the impact of recent form?

Form is one of the most frequently discussed concepts in football. Players, coaches, journalists and pundits routinely refer to the momentum generated by a succession of victories. Form guides are ubiquitous in pre-match reviews, the idea being that recent results are indicative of a team's chances of winning their next match. But is this idea founded in fact?

Looking for the impact of form, or momentum, in football is tough. There are a multitude of confounding variables, most notably variations in the quality of opponents, the effects of home advantage, changing team selections and small sample sizes. Situations are not replicable, making it difficult to study whether win probability has been enhanced by a recent run of victories. Nevertheless, there are some simple statistical tests that we perform to try to detect whether form has any impact on outcome of subsequent matches.

One test is to look at the frequency with which winning streaks occur. Streaks are a natural feature o…

Best Feet Forward: a willingness to wield the weaker foot

In first half stoppage time of a Serie A match last November, Bologna's Simone Verdi curled a free-kick with his right foot over the Crotone wall and past the two-handed dive of Alex Cordaz. Earlier in the half, Verdi had hammered a left-footed free-kick into the top corner of the Crotone goal. This may well be a unique achievement in the big European leagues: Verdi is the only player on record to have scored free-kicks with both feet in a single match. He appears to be right-footed (at least, he takes penalties with his right foot); yet, over the last four seasons, he has taken more shots with his left.

Genuinely two-footed players are a rare commodity (and appear to be paid accordingly). A study of 'footedness' during the 1998 World Cup found that less than a quarter of shots by right-footed players were taken with their left foot, and less than one in six by left-footed players were taken with their right. Only a tiny proportion of players appeared to be equally comfor…

Exceeding Expected Goals

From blogs to the BBC, the concept of expected goals (or xG) has entered the mainstream media's lexicon. It has caught on because it's a useful concept; it's a useful concept because football is a low-scoring game. Chance (or luck) can be the difference between victory and defeat, a good day or an off-day. Expected goals, however, measures what would have happened on an average day.
It's a simple quantity to measure. Shots are assigned a number between the 0 or 1: the proportion of similar shots (from the same position, for example) that have resulted in a goal. This number, sometimes referred to as chance quality, is then added up over every shot taken by a team during a match (or a season) to calculate the number of goals that you would have 'expected' them to score.
Conventional xG models do not take into account the identity of the player taking the shot. You need a dataset comprising many thousands of shots to properly measure chance quality over all posi…