Using Standard Deviation and Mean Absolute Deviation to rate Goalkeeper’s shot-stopping

For the last few years I’ve been dabbling with data in football, especially with data visuals that show performance or intention. For the most part I have only focused on that was familiar within the data and focused on representation of data and the manipulation of it. But since I’ve worked more and more with data in big datasets, I’ve also realised that differences in outcome also have a lot to do with the methodology you are using.

In this article I will focus on specific data metric and which score we can give each player. But, to do that I will also compare two forms of deviations to calculate a z-score: the Standard Deviation and the Mean Absolute Deviation.

Contents

1. Data
2. Shot-stopping explainer
3. Moving away from percentile ranks
4. Standard Deviation (SD)
5. Mean Absolute Deviation (MAD)
6. Z-scores
7. Best shot-stopper profiles
8. Final thoughts
9. Data

The data I’m using in this article comes from Opta. This Opta data has been released on the website of FBRef. The specific data was downloaded on March 21st, 2024.