Data For Dummies #2
Assessing creativity.
Data for Dummies is a new series on More Than A Game, with each article accompanied by a video broadcast on our YouTube channel.
Some say there is only one set of numbers that matters in football – the scoreline.
However, at More Than A Game we like to delve into the data to bring you closer to the biggest stories, to explain exactly what a player offers or why something is happening on the pitch.
After all, if the world's most successful clubs consult data when recruiting players and coaches, why shouldn't fans hold an interest in numbers?
With data becoming increasingly visible in the football world, we compiled this handy explainer to tackle some of the more ambiguous terms being thrown around.
In the second article of this new series, More Than A Game dives into creativity, and how we measure just how creative a player is.
And after reading this, why not check out the first article, as well as the accompanying video.
Chances created?
The most simple, broad-brush approach to measuring how creative a player is, is by using chances created (AKA key passes, though that metric traditionally excluded assists).
Simply using assists is no great barometer — an assist of course relies on another player to finish the chance, though it should be noted that the more chances a player creates, then by the law of averages, the more assists they should typically expect to get. But more on assists later…
Measuring via chances created is a good way to see just how creative a player is. Chances created can also be split down to those crafted from open play, and those from set-pieces.
Let’s look at this season’s leading chance creators in the Premier League this season.
Arsenal star Bukayo Saka leads the way, with 19 chances created in total — 12 of those have come from open play, and the other seven from set-pieces. Only two of these chances have resulted in assists.
However, when it comes to creating chances purely from open play, Tottenham winger Dejan Kulusevski is leading the way, with all 15 of the goalscoring opportunities the Swede has set up coming in general play. So far, Kulusevski’s creativity has gone unrewarded, with no assists to his name.
As for set-pieces, it’s Crystal Palace playmaker Eberechi Eze who tops the charts, with nine of the 16 chances he has teed up coming from a dead-ball situation. Fifth on this list is set-spiece specialist James Ward-Prowse; note how the West Ham midfielder has only created eight chances overall, but seven of those have come from free-kicks and corners, with only one from open play.
Chances created is a great way of measuring the quantity of opportunities, and we can further dive into just how creative a player is when we apply the metric on a per-90 basis.
Opta Analyst publicise some of these statistics, and so we can see that from open play, Phil Foden is actually the most creative player when it comes to the time he has actually spent on the field. For every 90 minutes the Manchester City attacker plays, he creates 2.74 chances from open play. Of course, this is a small sample size, though it’s no surprise to see the top of this list dominated by players from City and Brighton and Hove Albion — two of the most expansive teams in the league.
What is expected assists (xA)?
Expected assists (xA) measures the likelihood of any pass becoming an assist. Like expected goals (xG), xA is based on historical pass data. The pattern of play, where a pass is played from and received, and the type of pass are among the factors impacting the chance of a pass becoming an assist.
As with xG, passes are assigned an xA value between 0.01 and 0.99.
xA is a crucial metric for measuring how creative a player is, and much more useful than just looking at assists alone.
For instance, Bruno Fernandes led the Premier League for xA (16.7), though his actual return of eight assists showed huge shortcomings from his Manchester United team-mates when it came to finishing off those opportunities. Essentially, Fernandes finished last season with eight fewer assists than would have been anticipated based on the quality of chances he created.
And that’s the key difference when it comes to measuring chances created and xA. Chances created is a great way of measuring the quantity of opportunities a player tees up, whereas xA is a better indication of the quality of those chances.
For example:
Player A creates 50 chances during a season, but if those opportunities only have an average xA of 0.1 (10%), they are only producing a chance worthy of an assist once every 10 games.
Player B also creates 50 chances during a season, yet Player B’s average xA across those opportunities is 0.5 (50%), meaning he sets up an opportunity worthy of an assist once every two games. He is creating higher-quality chances than Player A.
So, let’s look at the players with the highest xA so far in the Premier League this term.
Like at the end of last season, Fernandes is currently leading the way, with 2.58 xA. The Portugal international has only set up one goal, so once again, his United club-mates are underperforming when it comes to the chances that have been set up by the midfielder.
Mohamed Salah, on the other hand, has four assists to his name already. However, Salah’s xA is 2.35, so we can see that his Liverpool team-mates are overperforming when it comes to finishing from the opportunities he tees up.
All data via Opta
By Patric Ridge
Patric is a data journalist at Stats Perform and is a regular contributor to Toffee TV and Opta Analyst, while he has attended high-profile events including the UEFA Super Cup and 2022 FIFA World Cup.