Friday, 23 September 2016

Premier League Excitement - Further Analysis

In my last post I looked at 'Howexciting is the Premier League' and produced the interesting data point that less than 10% of Premier League games are goal-less.  This may be interesting, and it might even count as insight, but it's not very actionable.  We can't do anything with it, or make any decisions from it.  I suppose the question is, "Is that a lot?" and I'll be looking at that question in more detail in future.

So, my next step is to look at how the different teams in the Premier League compare on some of the key metrics that I discussed - goals per game (total conceded plus scored), percentage of goalless games and so on.

Number of goals per game (conceded plus scored)

Firstly, I segmented the data per team:  how many goals were there per game for each team in the Premier League.  This is time-consuming, but worthwhile, and a sample of the data is shown below.  I have data as far back as the 2004-5 season, but the width wouldn't fit on this page: 
Club
Y2010
Y2011
Y2012
Y2013
Y2014
Y2015
Y2016
Arsenal
        2.58
        3.03
        3.24
        2.87
        2.87
        2.82
        2.66
Aston Villa
        2.21
        2.82
        2.37
        3.05
        2.63
        2.32
        2.71
Birmingham

        2.50





Blackburn
        2.79
        2.76
        3.32




Bolton
        2.61
        2.84
        3.24




Charlton
        2.47






Chelsea
        2.32
        2.68
        2.92
        3.00
        2.58
        2.76
        2.95
Crystal Palace




        2.13
        2.58
        2.37
Everton
        2.32
        2.53
        2.37
        2.50
        2.63
        2.58
        3.00
Fulham
        2.58
        2.42
        2.61
        2.89
        3.29


Liverpool
        2.21
        2.71
        2.29
        3.00
        3.97
        2.63
        2.97
Man City
        1.92
        2.45
        3.21
        2.63
        3.66
        3.18
        2.95
Man United
        2.89
        3.03
        3.21
        3.39
        2.82
        2.61
        2.21
Middlesbrough
        2.45






Newcastle
        2.24
        2.97
        2.82
        2.97
        2.68
        2.71
        2.87
Norwich


        3.11
        2.61
        2.37

        2.79
Portsmouth
        2.29






Southampton



        2.87
        2.63
        2.29
        2.63
Tottenham
        2.92
        2.66
        2.82
        2.95
        2.79
        2.92
        2.74
West Brom

        3.34
        2.55
        2.89
        2.68
        2.34
        2.16
Wigan
        2.53
        2.66
        2.74
        3.16



Season Average
2.77
2.80
2.81
2.80
2.77
2.57
2.70

Blank columns indicate a season where a team was not in the Premier League.  
Bold figures show where a team achieved over 3 goals per game for the season.
Y2008 indicates the season 2007-2008.
Firstly:  sorting alphabetically makes sense from a listing perspective, but for comparison the data is best sorted numerically (from highest to lowest). 

Secondly:  There's a lot of data here, and clearly a visualisation is needed:  I'm going with a line graph.  And to avoid spaghetti, I'm going to highlight some of the key teams - the team with the highest average number of goals per game; the team with the lowest, and the average.

Thirdly:  to identify the overall highest- and lowest-goal teams, I'm just going to take the totals of the averages for the last nine seasons, and sort them from the list.  Teams that were not in the Premier League for one or more seasons are included based on their performance while they were in the Premier League.

Premier League Teams:  Average number of goals per game over the last 12 seasons:


Club

Club
Average
Arsenal
      2.842
Tottenham
      2.833
Man City
      2.825
Blackburn
      2.816
Man United
      2.807
Liverpool
      2.781
Newcastle
      2.751
Norwich
      2.717
Bolton
      2.705
Overall Average
      2.702
Birmingham
      2.671
Chelsea
      2.670
West Brom
      2.669
Aston Villa
      2.667
Fulham
      2.613
Southampton
      2.605
Wigan
      2.566
Everton
      2.518
Charlton
      2.474
Middlesbrough
      2.404
Portsmouth
      2.368
Crystal Palace
      2.360

Key takeaways:  
- Arsenal have had the most total goals per game over the last nine seasons (2.842 goals per game)
- Everton have the lowest average number of goals per game for teams which have been present in all 12 seasons (2.518 goals per game).
- Put another way:  Arsenal fans have seen 1296 league goals in the last 12 seasons, compared to 1148 for Everton fans (148 fewer).


Theo Walcott, celebrating during Arsenal's win over Hull, Sept 2016  Image credit

Time for some graphs!

Firstly, average goals per season, for the last 12 seasons, for Arsenal, Everton, the league average, Liverpool (who achieved an average of 3.97 in 2013-14) and Man United (because they're always worth comparing).



This shows clearly that Arsenal (green line) have consistently exceed the league average, falling below it only twice in the last 12 seasons.  Everton (blue) have only once exceeded the average, and that was in the most recent season.  Liverpool have exceeded the average over the last four seasons, but prior to that were consistently below (and similar to Everton).

Connecting this to 'real life' events:

- Everton moving from David Moyes to Roberton Martinez in August 2013 did not make any difference to their 'excitement' factor until the 2015-16 season.

- Arsenal, and Arsene Wenger, could not be called 'boring' based on their goals per game. 

- Brendan Rogers had an interesting time at Liverpool, when they hit the highest goals-per-game for the season for any club in the last 12 years (3.97).  Note that this does not discriminate between goals scored or conceded.

Secondly, adjusting the data to show the difference between each team and the overall average (so that the data shows a delta versus the average).



To give you an indication of Liverpool's remarkable 2013-4 season:  their games had more than one goal per game more than the season average.  Brendan Rogers had an eventful time at Liverpool.

Fulham also had an 'exciting' season in 2013-4, achieving 3.29 goals per game (average was 2.77) - but were subsequently relegated.

In summary:
- Arsenal have had the highest average goals per game over the last nine seasons (2.842 goals per game), while Everton have the lowest, at 2.518 goals per game.
- Arsenal have exceeded the league average goals per game in 10 out of the last 12 seasons, and have the highest average overall.
- Man United have achieved above-average goals per game in nine of the last 12 seasons; however the 2015-16 season was the least 'exciting' they've recorded in that period.

Review
Segmenting the data by team is proving more useful.  It's now possible to make predictions about the 2016-17 season:
- Arsenal to remain most 'exciting', closely followed by Tottenham and Man City.
- Everton to remain the least 'exciting', with 1-1, 2-1 and 2-0 results dominating.
- Man United are extremely unpredictable, especially as they have a new manager this season (although nobody could have predicted the dreadful start they've made to the current season).

The raw data used in this analysis is available from the football data website, among others.


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