Thursday, March 29, 2012

A Statistical Look at the Race for European Qualification in the EPL

There are only eight matches left in the Premier League this season. The clubs from Manchester turned the race for the EPL championship into a two-horse affair long ago, so outside of the fan bases for those two clubs much of the league has been focused on the race for table positions three through five. Those are the coveted positions that gain a club entry to Europe, with the third and fourth positions guaranteeing a shot at Champions League glory next season and all of the money that comes with it. There are five clubs competing for those three positions - Arsenal, Chelsea, Liverpool, Newcastle, and Tottenham. Only three will find a seat at the European competition table when the music stops in May.


Of late, Arsenal has been streaking. Tottenham and Liverpool have been slumping. Newcastle and Chelsea have been plodding along.  Sitting on the outside looking in at a Champions League spot was too much for Roman Abramovich to stand and thus Andres Villas-Boas got the sack a month ago. Liverpool has been slowly fading as of late.  All of these are general observations deserve a bit more of a numerical examination to understand exactly what's been going on during one of the more volatile Premier League seasons in memory. Such an analysis cuts through the weekly "who's getting sacked" rumor mill and the volatility of match-to-match data that fails to see the forest from the trees.

In taking such a numerical view of the league, three measures of team performance are examined below.
  1. Cumulative Points Per Match - Total points accumulated divided by the number of matches played. This metric gives an idea as to the pace a team is on for PPM at the end of the season.
  2. Points Per Match (4 Match Running Average) - The average points accumulated per match over the previous four matches. This gives a running tally of the previous month's worth of matches, and can help highlight or quantify long term declines or rises.
  3. Table Position (4 Match Running Average) - The average table position per match over the previous four matches. This erases the volatility of weekly table position swaps and takes a bit of a longer term view of how a club's previous month's performance is translating to the their ultimate position in the table.
One gets an idea of how the season has played out when each of the metrics are plotted against match number. Graphs are presented individually below, with commentary attached to each and a forecast as to odds of how each team will finish the season.

Cumulative Points Per Match (PPM)


From the graph above (click to enlarge), we can draw the following conclusions:
  • Three of the five clubs reached their PPM peak by match 10. This isn't surprising, as a few wins to start the season can be a bit distorting to the PPM tally that settles out as sample size increases. What is interesting is that only one of these clubs - Newcastle - has been able to stop the inevitable decline and settle around a PPM of 1.6 +/- 0.1 points. If trend lines were drawn for Liverpool and Chelsea they would continue downward even at this late stage of the season.
  • Tottenham clearly had the best start to the season in terms of sustained form. They peaked by Week 13, and their peak PPM was only second to Chelsea. They too have seen a steady decline since then, but their long, sustained build of points should see them through to at least the fifth table position at season's end.
  • Arsenal's oft-chronicled slow start to the season is readily displayed in the graph. Even their mid-season slump can be viewed with the PPM drop from march 19 until match 23. However, taken in whole. it's clear that starting at match 10 the Gunners have been cycling between a PPM of 1.5 and 2. That suggests they've been in the thick of European competition since match 10 given the current PPMs of the other four teams. The start of the season was certainly a crisis in confidence for the club, but looking back it might be suggested that the righting of the ship took place much earlier than we all thought.
Points Per Match (4 Match Running Average)


While the graph (click to enlarge) above is a bit... messy, it does provide some additional insights into the streaks we've seen throughout the season. Here are some observations drawn from the graph:
  • On a monthly basis, Arsenal's early season form wasn't its nadir. Instead, it is found during a string of matches right after the mid-point in the season. Losses to Fulham, Swansea, and Manchester United and a 0-0 draw against Bolton at the Emirates lead to a month long average PPM of 0.25. Arsenal would begin their now-seven match winning streak in their next Premier League tie (a 7-1 win against Blackburn), although the beginnings of their improved league form were overshadowed by their 4-0 dismantling by AC Milan the San Siro two weeks after the Bolton draw. It should now come as no surprise that the Gunners came up one goal short of a historic turnaround two weeks later at the Champions League return leg at the Emirates, as we now understand Arsenal has been in top form for the last seven league matches.
  • If one looks closely at the graph they can see just how precipitous Tottenham's decline has been (yellow line). They reached their 4-match running average PPM peak of 3 points per match by the 13th match of the season. Since then, they've been on a steady decline for the next 17 matches, with only a brief spike around match 20 slowing the decline. In fact, it's remarkable how consistent the decline has been with an R-squared value of 0.724. Spurs have been losing a consistent 0.11 points per match from their 4-match running average since there December 3rd win against Bolton.
  • In an equal steep, but less consistent, decline is Liverpool. There latest peak 4-match running average was later than Tottenham's. Starting at Match 19 they've been on similar decline at an average clip of 0.09 points per match, although at a less consistent rate given an R-squared value of 0.60. The problem for Liverpool is that they started at a much lower peak value (2.0) and starting table position than Tottenham, and thus have fallen further in the table than Spurs. This performance has led many in the press to call for Kenny Dalglish's sacking, with perhaps his role of reversing the rot at Liverpool complete.
  • The graph clearly demonstrates the volatility of Newcastle's season.  What it also demonstrates is the painful drop in form at about the one-third mark of the season.  While their latest stumbles haven't helped, that earlier season drop in form is what has cost them dearly in table position.  It's a position from which the club has not been able to recover.
  • What must be most frustrating to Abramovich has been Chelsea's inconsistency throughout the season. The Blues dropped below the 1.0 point per match threshold - no better than a draw on average - three times during Andres Villas-Boas' tenure. The third time was the charm for Abramovich, sacking AVB only two matches after crossing this threshold for the third time. There's been a modest rebound in their play since his sacking, but it's a far cry from the level or performance required to squeeze into the fourth spot to get a Champions League play-in.
Table Position (4 Match Running Average)


The results of the previous two graphs are found in the graph above (click to enlarge) that looks at the 4-match running average of table position by club. One's perspective must be reversed compared to previous graphs - a line being lower on the graph is better for the club because it indicates a lower numerical/high position in the table. The table also demonstrates the deceiving nature of the table throughout the season, and why looking at running averages of PPM may be an earlier indicator of trouble or opportunity for a club.
  • The effect of both Chelsea's and Newcastle's hot starts and slow declines on table position are clearly seen in the graph.  Reflective of earlier comments regarding Newcastle's stabilization on a PPM basis, they've been a consistent fifth or sixth in the table for the last seven matches.
  • It appears Liverpool's never really been in serious contention for a Champions League spot, being no better than fifth the entire season on a 4-match running average basis.  Early season success was fleeting, and they've been on a steady decline since then at a rate of 0.07 places match.
  • Tottenham and Arsenal both demonstrate that it doesn't matter how a club starts the race, but rather how one finishes it.  A 38 match season is a long affair, and as much as Tottenham started the season hot, Arsenal seems to be poised to finish it even hotter.  How frustrating might it be for Tottenham and their supporters to see such a glorious start to the season possibly end in fourth to a club that didn't make it halfway up the table until a quarter of the way through the season and into the top 25% of the table until the season was nearly half complete?
  • Here's a statistic to put Arsenal's steady climb into third into perspective.  Since the Gunners crossed the 7th position barrier on 4-match running basis at match 12, they've moved up the table at a 0.13 position clip per match.  That's a table position every 8 matches.  Slow, but steady, wins the day.
Outlook for the Rest of the Season

So how will the season turn out?  I don't have such prognostication skills (yet), but there are multiple options for forecasts via the web.  One of my favorites comes from Sports Club Stats.  Their website not only provides the odds of a team winning the next match or the Premiership, but also the odds of finishing in any table position given their current point total and the opposition they face the rest of the season.  If one clicks on a team of interest they'll find even more details, like the odds a club finishes in different table positions given their final point total, and the odds for each table position given the multiple win/draw/loss combinations that can add up to the corresponding final point total.  It's quite a neat site.

Given that the site is updated at the conclusion of each match weekend I have grabbed this week's data and compiled it in the table below.  Each club's odds of finishing in 3rd through 7th or outside of 7th are shown within the table.


A few conclusions can be drawn from the table:
  • Arsenal appears poised to maintain their streak of Champions League qualifications, making it into the competition for the 15th straight year.  With an 8 point lead over Chelsea with only 8 matches to go, Chelsea would have to earn more than a point per match more than Arsenal the rest of the way.  That is something they've only done three times so far this season (on a 4-match running average basis).
  • Tottenham are close behind Arsenal, with a less than 15% chance of not making it into next year's competition.  There be a small bit of a crisis of confidence if the late-season swoon gives Arsenal the third position and Tottenham must play-in to the tournament, but one would suspect it's something the players could get over and secure England a fourth entrant into the group play stage of next season's Champions League group play stage.
  • Barring further decline by Tottenham, Chelsea will be on the outside looking in when it comes to Champions League qualification.  They only have a 15% chance of making it into the tournament, and a nearly 30% chance of not even qualifying for the Europa League.  Will Abramovich's club take UEFA's second tier competition seriously next year, or choose instead to focus their efforts on the league to secure a Champion's League berth for 2013-24?  This off season will be very odd at Stamford Bridge - perhaps no trophies, no Champions League next season, and a club that anyone would agree is in decline in the two short years.
  • Newcastle United will be able to hold their head high, likely finishing 6th or better only a season after finishing 12th.  Things will be looking up at St. James Park in the off season, having worked their way steadily up from promotion to the Premier League only two seasons ago.  They may even get lucky, with a 31% chance of pipping the likes of Chelsea for 5th position or higher and a spot in Europa League.
  • Things at Anfield are not good.  The Reds have a greater-than-even odds of not even finishing in the Top 7, a step backwards from last season on a table basis and the performance in 2009-10 that got Rafael Benitez sacked.  In fact, it would be their worst finish in terms of table position since 1993/94.  There is no doubting the turnaround Kenny Dalglish led at Liverpool when they had reached the nadir of what was effectively the Hicks/Gillette regime.  However, one can't help but the feel the magic has worn off and the honeymoon is over when a comparison is made between this season's performance and the one in the second half of last season.  There are few excuses to be had.  Liverpool is under performing, and one must wonder how long King Kenny will keep his job.
No matter what the odds say, the last eight matches of the season will provide for some compelling soccer.  Will Manchester City win their first ever Premier League title or will United fend off yet another challenge to their long-term supremacy within the league? Which of the two bitter North London rivals will gain automatic entry to the Premier League?  Will Chelsea be able to slip into Champions League qualification, or might they even fall out of the Europa League qualifying spot?  Might they even pull off the unlikely feat of winning the Champions League, thus fulfilling one of Abramovich's long held goals and denying the fourth table position entry into the competition?  Will Liverpool stumble to their worst finish since the 1993/94 season?  Only the final eight matches will tell.  It's going to be an exciting end to the season!

3 comments:

  1. Just wanted to make a quick point that Liverpool is already in the Europa League due to winning the Carling Cup . . . if they happen to qualify via league table position, I believe that means Cardiff would get in, and more craziness would ensue. Also, they are still in the FA Cup, so that's definitely another route for them (as well as Tottenham and Chelsea). Everton could definitely throw a nice wrench into things though by at least beating Liverpool in the FA Cup. We'll see!

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  2. Tim - you're the second person who has pointed out Liverpool's qualification for Europe. Given that I made passing mention of Europa League in regards to Chelsea, I probably should have been fair to Liverpool and mentioned it when discussing them as well. Thanks for reading, and I hope to not make a similar mistake again!

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  3. I probably should have been fair to Liverpool and mentioned it when discussing them as well. feng shui

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