The price of playing in the Champions League

October 3rd, 2010

Unbeaten title contenders Ajax succumb to an even unexpected as rare home loss at the hands of Utrecht, after conceding two early penalty goals and managing only a dying minutes come back goal.

Earlier that week: Ajax – Milan 1-1.

 

November 7th, 2010

Second league defeat for Ajax, at home again, against ADO this time. Regular Eredivisie followers will probably recall prolific winger Wesley Verhoek as the scorer of the only goal of the match.

Earlier that week: Auxerre – Ajax 2-1.

 

December 12th, 2010

Twente’s biggest loss of the season: the Oussama Assaidi show finishing in a 6-2 home win for Heerenveen. At the hand of the creative dribbler Heerenveen put six past the reigning champions.

Earlier that week: Twente – Tottenham Hotspur 3-3.

 

Incidents?

Or a structural price to pay for competing at the highest level of European club football? Of course, picking a few examples to illustrate a case is nowhere near where you want your research to be, but these matches did trigger the idea behind the current article. Let’s look at the performances of the Dutch clubs competing in the Champions League and compare the results in the immediate post-CL Eredivisie matches (if played within five days) with the results obtained in Eredivisie matches that were not preceded by a CL match.

 

Analysis

For comparison, the results obtained by teams competing in the Europa League will be thrown in too. Ajax’ matches in the Europa League during the later stages of the 2010/11 tournament were considered among the CL group as the advanced EL tournament is considered to represent a comparable challenge to the CL group stages. Matches involving two teams that both played in either the CL or the EL earlier that week were considered among the non-CL/EL group as the effect of the European football match was considered to be cancelled out.

 

Results

Over the past three seasons four Dutch clubs participated in the Champions League: Twente (2010/11), Ajax (2010/11), AZ (2009/10) and PSV (2008/09). Among those, only Ajax in the recent season ran out winners of the Dutch league, while the other three clubs finished 2nd (Twente), 5th (AZ) and 4th (PSV), respectively.

The four CL participants finished on average on 67.8 points (or 1.99 points per game, PPG), while the EL participants finished on 60.9 points (1.79 PPG).

The CL participants played on average 8.3 post-CL matches, while the EL participants played 6.8.

The average PPG results for CL and EL participants are shown in the graphs below, split out between matches within five days of European football and matches not preceded by European football in the five days before.


Surprisingly, the results contrasted sharply between the Champions League and Europa League contenders. While the teams participating in the CL produced a lower PPG (-0.25) in league matches shortly after European football, the teams participating in the EL actually managed a higher PPG (+0.29) in those matches.

The effects were more pronounced in away league games compared to home games with CL contenders managing -0.14 PPG in home and -0.44 PPG in away matches and EL contenders +0.22 PPG in home matches and +0.42 PPG in away matches.

 

In conclusion

This small study on the effects of competing in Europe on the results of domestic football comes up with some surprisingly different results for Champions League and Europa League football. The data, of course, do not tell what might be the cause of this phenomenon, if it is at all a real effect and not induced by the relatively small sample size.

If we assume that it is indeed a real effect, then the positive effect of EL matches suggests a positive stimulus by those matches, while the negative effect of CL competition on domestic results suggests a burden induced by competing at the highest level.

If we compute the expected points effect over a season, the average of 8.3 CL matches would mean 2.5 points dropped, while the average of 6.8 EL matches would mean 2.2 points won. With the past two seasons decided by two points and one point respectively, in a league as tight as the Eredivisie this might just make the difference between winning the title and just falling short.

4 thoughts on “The price of playing in the Champions League

  1. george

    What if you did the same thing with EPL or La Liga teams? I imagine they’ll have a much larger sample size.

    Reply
  2. Jasper

    You could use Welch’s t test (or ANOVA) to see if the difference between ‘post EF’ and ‘not post EF’ is significant for CL and EL, otherwise you can’t tell if it’s real or just chance.
    http://en.wikipedia.org/wiki/Welch%27s_t_test

    Also, one wouldn’t expect Ajax to lose against ADO at home, but it’s also not particularly shocking since ADO played and did well this season. Ajax losing to De Graafschap for example would have been much more surprising.
    Because the dataset is relatively small, I doubt you can assume weaker and stronger opponents to be evenly distributed in ‘post EF’ and ‘not post EF’. You might as well have shown that the KNVB scheduling isn’t random enough. Then there is the problem of home advantage, injuries, etc.
    If you really want to examine the difference between ‘post EF’ and ‘not post EF’, you would have to account for relative strength somehow (betting odds?) or drastically increase the number of seasons examined. But then you probably would have to quit your day job.

    Great blog by the way, I really enjoy reading it.

    Reply
  3. Tom

    Thanks for the blog, I enjoy reading it.

    Interesting post. I was going to say exactly what Jasper said—you need a statistical test to know whether the ‘points per game’ figures are actually different (especially since the figures are so close). And then, even if it’s significant, you’re still not 100% sure what effect you are measuring.

    Reply
    1. 11tegen11 Post author

      Jasper and Tom, thanks for your comments. I fully agree with you that these kind of analyses need significance testing, which might be a future direction to take. This would probably go along with extending to figure to other European leagues, as the hypothesis that “competing on two fronts in one week reduces the amount of domestic points won” is expected to hold throughout different leagues.

      Reply

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