Monday, November 30, 2009

EPL Update - Chelsea Clear Top

With the big win over Arsenal at Emirates, Chelsea cemented their place at the top. The blues remain 5 points clear of Manchester United and are now 11 points ahead of the Gunners, with Arsenal having a match in hand. Looking ahead to December, Chelsea have Man City next and then a pretty comfortable list of fixtures: Everton, Portsmouth, West Ham, Birmingham and Fulham. They have a great shot at being in a dominant position come the break. They will have to be good though since Manchester United has a pretty similarly easy schedule for that stretch. I thought it would be different but at this point it's tough to see anybody but those two winning it, with Chelsea the favorite at the moment.

Here's the updated rankings:

Again, the last column is the expected goal differential if these teams played out a full season at the level shown so far.

Someone asked me when I expect these numbers to start to converge. I don't have a good answer to that and it's something I'll be looking into. They will certainly converge at the end of the season which is a nice feature of the model. Most teams have played 14 matches, which by the way is right around the number of matches for a World Cup qualifying campaign. I think things should be pretty good, but because right now the model only uses goals and no other statistics, it is still subject to randomness.

When I was checking on the numbers, I discovered something interesting. I've said before that teams like Arsenal and even Chelsea are overrated when it comes to scoring as they've likely been running over expectation. The reason for that is that the model predicts an expected goals of 108 for Arsenal and 97 for Chelsea when both clubs scored 68 goals last season with similar rosters. The model accounts for schedule so it's a bit different, but both of those clubs are on pace for about as many goals as the model says. When I compared other clubs' expected goals with last season, I discovered that 14 of the 17 teams that played last season in the EPL have a higher expected goals scored.

I thought this might be a problem with the model, but for all matches thus far the average number of combined goals is 3.04. Last season it was 2.21. If scoring stays at this pace, there will be about 318 more goals scored this year than last year in the entire league. I have no explanation for why this would be the case, but scoring seems to be up in a big way. I'm going to write another article or two for the stats series but this raised another interesting question which I'll write about. I wonder if scoring is often higher in matches in the early part of the season compared to later.


  1. It does seem that my predicted bottom 3 (Hull, Wolves and Portsmouth) are falling into place. But Hull seemed to have a mini-revivial with 4 points in 2 games. If they continue with this good form, I don't think they deserve to be in the bottom 3 come May next year.

    Apart from the mini juggle in the bottom half, there are no major changes in the table. I worry for Everton though, as they face Tottenham and Chelsea next, which might see them drop even further down.

    That being said, some of the bottom teams do have tough fixtures coming up in December as well. Wolves have Man Utd, Tottenham, Liverpool, Man City in December, and Portsmouth have Arsenal, Chelsea and Liverpool. These two could potentially lag behind the lot as we move into 2010.


  2. Just to add another comment about whether the early part of the season will see more goals, personally, I don't think that's the case.

    I don't really know the exact figures, but I guess it's roughly the same with some fluctuation (like a head-tail coin toss). As for why the average goals per game is so high this season, I guess it's just due to variability. (Due to different managers' approach to the game?)

    If the population mean (which we won't know) is below (or above) 3.04, then perhaps we might see a drop (or an increase). But if the population mean is around 3, then I guess this figure will remain approximately constant.