Football Hackers: The Science and Art of a Data Revolution
Link:
https://books.google.com.sg/books?id=uiCIDwAAQBAJ
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(The normal service resume part kinda apply for Dortmund, given they were 17th at winter break and finished the season 7th)
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At winter break of 14/15:
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A first look at the numbers tells me that Dortmund certainly aren’t playing like a relegation threatened team. Our Expected Goals model (which basically assigns the probability of each shot being scored) has Klopp’s team in for scoring approximately 25 goals so far this season and a conceded total of 17 goals; this gives an Expected goal difference of +8 goals. The reality of what happened on the pitch is very different however, with the concession of 26 goals dwarfing the 18 goals that they have actually scored – that is a swing of 16 goals between the Expected Goal Difference as calculated by us and their real Goal Difference. And all of that occurred in just 17 games.
It is sometimes possible for a team to under perform their Expected Goal Difference without having a significant adverse impact on their league position. For example, a team may win by just 1 goal despite an emphatic performance, or get beat by 3 or 4 goals when the numbers would suggest that they should have suffered a narrow defeat. In both these cases the underperformance of Expected goals doesn’t actually cost the team any league points.
Unfortunately however, Dortmund have not had the good fortune to be in this position this season as they have recorded six single goal defeats and three draws from their 17 league games played. In other words, an additional goal here or there would almost certainly have resulted in additional league points for BVB.
Using our ExpG model, when I run thousands of simulations on all the shots taken in the games played so far in the Bundesliga this season I arrive at a league table that looks as follows at the top:
It’s noticeable that, with the exception of Dortmund, all of the other teams have approximately as many league points as our model has predicted.
Not only do I not have Dortmund in relegation trouble, but I actually have them in 4th position and, on my simulated table, they are within 1 league point of Wolfsburg.
The lack of league points won by Dortmund this season, given the shots taken in their games, is extraordinary. The extent of their underperformance in terms of Expected Goals and actual goals is not something that I think I have seen before and
even if their underlying performances don’t improve I’m confident that it’s only a matter of time until Dortmund begin their ascent up the table.
Despite that assertion I wanted to take a look at some of the metrics I keep an eye on to see if I could pick something else out that might help us get an idea of what has changed for the Black and Yellows this season.[/article]
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Some of Dortmund’s defensive lowlights:
- 15% of all shots taken against them have been scored (this is the highest in the league)
- Allowed 6.3% of shots taken from outside the penalty area to be scored. The league average is 3.6% and only Leverkusen (7.5%) have conceded a higher percentage this season
Our model expected Dortmund to concede approximately 16.5 goals so far this season; however they have conceded 26.
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