I’ve been playing around with some different ways to visualise a player’s scoring/assisting rate over a league season these past few days. Raw numbers relating to these can often seem a little deceiving; you often hear ‘player A has scored x number of goals in x number of games’, but this gives no information about things like minutes played, or whether player A is primarily a starter or a substitute.
This problem has already been discussed in depth at Statsbomb, where the per90 metric is frequently used. Assessing a player based on contributions (whether it be goals, assists, etc.) per 90 minutes is great because it can give a standardised number based on minutes on the pitch and provide a less coarse analysis of these contributions. But how can we visualise this?
At first I was just interested in scoring rate, and knocked up a couple of graphs looking at Thierry Henry at Arsenal, and how his goal total developed over the course of each season.
This was ok, but too simplistic, and ignored information about minutes played. That wouldn’t be an issue if player A plays every minute of every game, but that is rarely the case, particularly for attackers. So next I tried to incorporate starting/substitute information:
These show information about whether a player started a game, was used as a substitute, or did not play. We now have a little context over why Henry’s scoring tally doesn’t increase in certain periods: red markers indicate that he did not play. We now also have some information about how often he was introduced as a substitute. This can be useful when assessing players who are in and out of the starting eleven. Here is Javier Hernandez in 2011/12:
This still isn’t quite there though. How many minutes did archetypal substitute Hernandez play each time he came on? Plus, starting a game doesn’t always mean playing 90 minutes (unless you’re pre-Martino Messi). I kept using the markers as information points for minutes played, but messed around with different colours to represent time on the pitch. Here’s Hernandez again:
The darkest blue markers represent games in which Hernandez was on the field for the full 90 minutes. The medium blue represents instances in which he played more than 45 minutes, and the lighter blue times he played less than 45 minutes. I kept the red markers to indicate when he did not play at all. We can now see just how infrequently Hernandez completes 90 minutes, and how many minutes he plays as a substitute roughly.
These can also be used not just to look at individual players, but to make comparisons between rival players or players on the same team. By plotting Daniel Sturridge and Luis Suarez this season for Liverpool, we can see how much they’ve played together (although overlap makes this one messy).
Plus, we can forego starting/substitute information in some rare cases where players get 90 minutes each game for the vast majority of the season:
These are clearly not perfect, and ideally I would like to find a way to make these graphs interactive, so a viewer can see minutes played, opposition, home/away information, etc., but I don’t yet have the skills to go this far. Still, I like looking at player information this way, so will probably keep working on getting these a little better at representing minutes played.
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