Return of the E Ratings: League 1: 21 Jan 2018

Quick intro / recap

At the start of the season I mentioned that there would be a bit of a delay in getting the E Ratings live again. There were two reasons behind this:

  1. The official data being collected for the National League, which had for years been at the same level as the EFL, was cut back significantly (presumably for cost reasons). To me this feels like a huge backward step that they’ll ultimately regret, but (that aside) it also broke the model, which needed that data to establish a starting rating for newly-promoted clubs from that division.
  2. I wanted to make the model better, having read a slew of interesting posts over the summer about approaches that could potentially improve it, so I took it to pieces and started to rebuild it from the ground up. However towards the end of the summer my team at work won some additional contracts that soaked up most of my free time, so I kept having to park it.

I’ve still not gotten around to addressing (2), which is a huge job and needs a stretch of unbroken time (and lots of testing) devoted to it, but I was starting to get sick of not having the ratings around so I’ve slapped the old model back together and come up with a quick fix for (1) – basically using actual goals instead of expected goals to feed the ratings – which will have to do for now.

Latest ratings

Here is the latest update of the season to the E Ratings and how they predict the rest of the season will pan out. The rating system is explained here, but in a nutshell it’s based on the combined quality of chances that clubs create and allow, rather than their results.

The attack rating broadly equates to how many goals’ worth of chances a team would create against an average opponent (so higher is better), with the defence rating equivalent to the chances they’d be expected to allow (so lower is better). The overall rating is the difference between the two – effectively the average expected goal difference per match – so a positive number is good and a negative one is bad.

The graphic below lists each club in descending order of their overall E Rating and shows how this – along with their individual attack and defence ratings – has changed over the past 30 league matches. The red and green arrows indicate how the overall rankings have moved in the past month and the numbers in brackets show the ranks for each team’s attack and defence ratings.

Wigan and Blackburn are the only two clubs with a realistic claim to be considered the division’s best as it stands, with the Latics some way out in front. Bradford and Rotherham stand out as the next most impressive performers overall.

Both Shrewsbury and Oldham have improved their ratings massively this season, with the latter the more dramatic after a successful change in managers.

Gillingham, whose improved results this season far outstrip any change in their underlying performances. The data suggests that this is a bubble which could burst, although as we’ll see below they could already have secured their survival regardless.

Predicting the rest of the season

Below I’ve used each club’s current ratings and those of their remaining opponents to predict how the rest of the season could play out. Each of the remaining fixtures has been simulated thousands of times, using the current E Ratings to generate probabilities for where each club will finish.

This graphic shows the cumulative probability of where each club could end up, in descending order of average points won. You can think of the ordering of the teams down the left hand side as a “best guess” of the final league table, with the coloured bars showing the relative likelihood of each club ending up in a certain section of the table:

Wigan and Blackburn are looking increasingly nailed on for the top two places, with Shrewsbury their only realistic challenger as it stands. The final play-off place remains up for grabs, with Rotherham and Charlton currently likeliest to acquire it while Peterborough and Portsmouth remain outsiders.

At the bottom, Bury look pretty screwed with Rochdale, MK Dons and Northampton the likeliest to join them in the bottom four. However with so many relegation places there remain a lot of teams who could be dragged into danger.