In 2014 I created an Index to measure team performance; my goal was to create one number (exclusive of points scored) that could help me tell a story about team performance that isn’t just about goals scored and goals against (Goal Differential).
While I can’t share the internal data points and algorithms anymore I can offer the Index is designed to capture the ‘primary bell curve’ of team activities on the pitch.
Here are diagrams of the Indices for each league/competition originally measured in 2014. The ‘r’ in each diagram offers the correlation of the Possession with Purpose Total Soccer Index (PWP TSI) to points earned in the league table.
Points earned is not a data point in the algorithm used to create the Index.
Since the TSI was first created in 2014 I’ve updated the algorithm to try and exceed the ‘r’ of Goal Differential to the league table – a long-time benchmark of accuracy and one of the primary reasons the statistic Expected Goals was created.
That logic follows the premise that it’s all about goals scored and goals against.
In 2018 I updated my algorithm and for Major League Soccer the TSI now has a greater correlation (r) to the league table than Goal Differential.
With World Cup 2018 nearly here I will be testing my Index again – and comparing the accuracy of my new algorithms to what was generated during World Cup 2014.
Here’s the World Cup 2014 Index showing the new TSI compared to the previous TSI and Goal Differential:
The green cell shows the Attacking half of the new TSI has a greater correlation to points earned than either the new Composite TSI or Goal Differential.
The days of using Expected Goals as a predictability model for scoring goals is over.
This should also convince Anderson and Sally that it isn’t all about preventing goals scored; at least not in the World Cup of 2014.
Look to my site if you want to see how your favorite team is comparing against the rest of the world.
Here’s a reminder of what the PWP TSI showed at the end of group stages in World Cup 2014.
Germany and Argentina (the two finalists) were 1st and 3rd in the Index.
If an American it should be pretty obvious the USA was punching way above their weight in making it past the group stages. If you want to know my thoughts (back then) on the future of Jurgen Klinsmann and Sunil Gulati – click here.
Perhaps this years’ Index will be as telling as the one in 2014?