On Holiday

I am currently on a trip with my family and will probably not be able to post anything until early next week. I may have access in the next few days, in which case I'll probably post on the Spanish league since they come back this weekend and the other leagues have more time off. When I get back home, I'll post a half-time report on each of the top leagues. Next week I hope to get back on track with more general articles about the game. I plan to continue the stats series and am working on analyzing derbies to determine if they are any different than regular matches in terms of predictability and in factors such as home-ground advantage.

EPL Boxing Day to 2010 Preview

As usual, the last week of the year is filled with English football. This season the fixtures list is as well organized as Germany sitting on a 1-0 lead. Each club plays one match at home and one away. Most clubs play on Boxing Day and then again two days later. There are, however, two matches on the 27th, 29th and 30th so after Christmas you are covered until New Year's Eve.

I'm going to make this a long preview, going through each club starting at the top of the table.

Chelsea
at Birmingham the 26th
vs Fulham the 28th

Chelsea are relatively injury free, they should only be missing Essien and Bosingwa. Essien, who was hurt two weeks ago in a meaningless Champions League match, is a huge loss but their injury situation is not nearly as bad as their two main rivals for the title. Chelsea have two fairly tough matches. While they are favored in each match, they are underdogs to win both of them.

The model says:
Expected points: 4.44
6 points: 45.3% chance
4 points: 27%
3 points: 17.5%
2 points: 3.8%
1 point: 4.9%
0 points: 1.5%

Manchester United
at Hull the 27th
vs Wigan the 30th

It seems like the Red Devils are missing just about everybody. Certainly out for both matches are van der Sar, O'Shea, Evans, Ferdinand and Hargreaves. Nani should be out for both as well. Probably out for the first, and maybe out for the second as well are Vidic, Giggs, Neville and Brown. The good news if you're a United fan is that both matches are against weak opponents. In fact, Hull and Wigan are the worst in the league in goal differential.

The model says:
Expected points: 4.96
6 points: 60.3% chance
4 points: 22.5%
3 points: 12.8%
2 points: 1.8%
1 point: 2%
0 points: 0.6%

Arsenal
vs Aston Villa the 27th
at Portsmouth the 30th

Arsenal are also in bad shape as far as injuries go. van Persie, Rosicky, Gibbs, Clichy and Bendtner will be out for both matches. Traore and most importantly Fabregas are questionable for the first match against Villa. That match should be a great one that is big for both sides. I think the Portsmouth match will be tougher than it appears as well. Arsenal should be ok and playing later than most teams should help them slightly since it give Cesc an extra day to heal. Plus they get two days off in between instead of the more common one.

The model says:
4.14 expected points
6 points: 37.5% chance
4 points: 28.0%
3 points: 20.3%
2 points: 4.9%
1 point: 6.9%
0 points: 2.4%

Aston Villa
at Arsenal the 27th
vs Liverpool the 29th

If you are a neutral and have to watch just one club this week it should probably be Villa as they play what look like the two best fixtures. Heskey went down with a groin strain last weekend and is questionable for both matches, otherwise they are healthy. That's good news as they'll need to put full effort into both matches against potential rivals for European spots. Their second match may be extra tough since they only have one day off in between whilst Liverpool will have two.

Expected points: 1.84
6 points: 4.0%
4 points: 9.9%
3 points: 27.1%
2 points: 5.7%
1 point: 27.3%
0 points: 26%

Tottenham Hotspur
at Fulham the 26th
vs West Ham the 28th

Two fairly tough matches await Spurs who are hoping to take advantage of recent form. Nothing new on the injury front. They will still be without Woodgate as well as the out-of-favo(u)r Bentley. Luka Modric, returning from breaking his leg last August, came on as a sub on the 12th against Wolves but did not play against Man City. He may not start both matches but it seems like he should play in one or both matches. Given Aston Villa's two matches, this would be a great opportunity for Spurs to slide into the fourth Champions League spot, at least temporarily.

Expected points: 3.72
6 points: 25.3%
4 points: 27.3%
3 points: 31.5%
2 points: 4.4%
1 point: 8.3%
0 points: 3.2%

Man City
vs Stoke City on the 26th
at Wolverhampton Wanderers the 28th
Expected Points: 3.98

Birmingham
vs Chelsea on the 26th
at Stoke City on the 28th
Expected Points: 1.91

Liverpool
vs Wolves the 26th
at Aston Villa the 29th
Expected Points: 3.88

Fulham
vs Tottenham the 26th
at Chelsea the 28th
Expected Points: 1.9

Sunderland
vs Everton the 26th
at Blackburn the 28th
Expected Points: 2.65

Burnley
vs Bolton the 26th
at Everton the 28th
Expected Points: 2.6

Everton
at Sunderland the 26th
vs Burnley the 28th
Expected Points: 3.09

Wigan
vs Blackburn the 26th
at Manchester United the 30th
Expected Points: 1.94

Hull
vs Manchester United on the 27th
at Bolton the 29th
Expected Points: 1.28

Bolton
at Burnley the 26th
vs Hull City the 29th
Expected Points: 2.91

West Ham
vs Portsmouth the 26th
at Tottenham the 28th
Expected Points: 1.98

Portsmouth
at West Ham the 26th
vs Arsenal the 30th
Expected Points: 1.99

EPL Pre Boxing Day Rankings Update

In a week that featured a midweek matchday, there were a lot of interesting results. Most surprising was probably Fulham getting a 3-0 home win against Manchester United. Fulham getting a win over Man U at Craven Cottage isn't too surprising by itself but the scoreline is. Granted, United have had a lot of injury issues lately, and the score was unfair but the result is still eye-opening. The other big upset I suppose was Liverpool losing 2-0 to Portsmouth. It's similar to Fulham - Man United in that it's not the most amazing result ever but still unexpected. Liverpool have been hemorrhaging points lately, and in my view Portsmouth aren't as bad as their points or status at the bottom of the table indicate.

The big winners of the week were probably Spurs and Aston Villa. While all the other clubs near the top faltered, both got the job done. Spurs ran through Manchester City in the midweek with an impressive 3-0 win. Having watched this one I think the scoreline was fair; Tottenham dominated for most of the match. They wrapped things up with a 0-2 win at Blackburn. Villa's two wins weren't particular impressive, 0-2 at Sunderland and 1-0 against Stoke City but they count all the same and the other teams around them, Spurs excepted, all slipped up.

Here are the updated rankings. I'm including more info on the first chart. These are the rankings based only on the number of goals in each match:

EGF - expected goals for
EGA - expected goals against
EGD - expected goal differential
Change - change in expected goal differential from last rankings (14 Dec)
expected goals for/against are the average number of goals scored/conceded by the club if they all played a new season at the level shown so far by all results.

Here is the rankings based on stats as well as results:

EP is the expected number of league points if they played a new season at the level shown so far. Change is the change in expected points since I posted the last rankings on 14 December.

One of the nice features of adding stats is that because there is more information they are less prone to move based on one or two good or bad matches. You can see that above, though keep in mind that a difference of 1 goal in goal differential is a change of about 2/3 of a point. Even taking that into account the average difference is about 3 times as large in the goals-only model compared to the one that also uses match stats.

Effect of Boxing Day Glut of Matches

The English Premier League is unique among top flights in that they play a lot of matches between Christmas and the first few days of the year while most leagues are completely off. Most seasons a team will play on Boxing Day and then again just two days later. Some seasons there will be another match just 2 or 3 days after that so they are playing 3 league matches in 6 or 7 days. This year there are matches every day from the 26th to the 30th of December. Most teams play on the 26th and then on the 28th.

Does this sequence of fixtures help any type of team? It seems like it could go either way. The good teams tend to be deeper in talent so the short amount of rest could help them as they can start fresh players that are still at a high level. On the other hand, fatigue could add some randomness to the short-rest matches. That is probably good for the bad teams since it makes upsets more likely. Perhaps the most sensible guess is that it doesn't really matter; both teams face the same strain.

To test this, I came up with a simple model with just one input for all matches and another for the matches played on short rest during the last week of the year or the first few days of the new year depending on the schedule. The data is all matches since the 1995-1996 season. The input is the difference in average goal differential for the home and away teams in all matches other than the one in question. So instead of the predictive model, I'm actually using data from after a given match took place. For example, if the match is Arsenal at home against Everton two seasons ago I'll take Arsenal's goal differential for the season, subtract off their goal differential in that match, and divide by 37. I then do the same for Everton and the input value is the difference. I then include another variable which takes on 0 for all matches other than those with short rest at the end or beginning of the calendar year. For the matches we are interested in, the value is the same as the other - the difference in average goal differential between the home and away team in all other matches. I then ran those through an ordered logit model to see if there was a difference between the short-rest matches just after boxing day and the regular ones.

In case that didn't make sense, the only thing you need to know is that if the coefficient on the short-rest variable is significant and positive, then that means that the shortened rest favors good teams. If it is significantly negative then that means that the schedule favors bad teams making them more likely to get a result against better sides. If it is very close to zero either way then that indicates that the difference in schedule from the rest of the season doesn't matter either way.

As it turns out, there is no evidence of an effect either way. The coefficient was 0.12 with a standard error of 0.167. The standard error being larger than the value of the coefficient means it is very likely that the difference is just due to randomness. The p-value is 0.472, meaning that there is about a 47% chance of values this extreme if the actual value of the coefficient is 0. That's quite high. There is no evidence of any difference between the post-Christmas group of matches and the rest of the season.

There are reasons to dislike the scheduling, I'm sure players don't like playing so frequently in such a short period of time, but it appears that fairness isn't a factor as it doesn't overly benefit or punish good or bad teams.

EPL Predictions

To be honest there aren't any big matches this weekend so I'll just give you the predictions of the stat-based model.

Portsmouth - Liverpool
Portsmouth - 21%
Liverpool - 53%
Draw - 26%

Aston Villa - Stoke City
Aston Villa - 63%
Stoke - 15%
Draw - 22%

Blackburn - Tottenham
Blackburn - 25%
Tottenham - 47%
Draw - 28%

Fulham - Manchester United
Fulham - 22%
Man United - 51%
Draw - 27%

Manchester City - Sunderland
Man City - 67%
Sunderland - 13%
Draw - 20%

Arsenal - Hull
Arsenal - 90%
Hull - 3%
Draw - 7%

Wolverhampton - Burnley
Wolves - 42%
Burnley - 29%
Draw - 29%

Everton - Birmingham
Everton - 53%
Birmingham - 21%
Draw - 26%

West Ham - Chelsea
West Ham - 9%
Chelsea - 75%
Draw - 16%

Bundesliga Update

It's been a while since I wrote about the Bundesliga. In my last post on the subject, I noted that Leverkusen were at the top of the table and had played a very easy schedule. Based on that, I predicted that they would extend their lead which was then at 3 points. That hasn't happened. After drawing in Munich and crushing Stuttgart at home they have two disappointing draws - at Hannover and then last Friday against Hertha Berlin. I still believe that they are the best team, but the gap is small and I could certainly see them falling.

On the other side, Bayern Munich seem to have found a rhythm. They won their last three matches, albeit against bottom half of the table opponents, by a combined 8 goals. They also destroyed Juventus in Torino in a match that was crucial for both sides. With the draws by Leverkusen, Bayern find themselves just two points out. That's a far cry from where they were last I wrote. I'm not ready to make them favorites but I definitely think they have a better shot now than I did before.

Here are the results-based rankings:



GFR - Ranking by goals for, adjusted for schedule
GAR - Ranking by goals against, adjusted for schedule
EGD - expected goal difference if they played a new season starting today at the level shown by results.

Here are the rankings using the model that incorporates stats:



Epts is the expected points if they played a new season starting today at the level shown by results and stats from all matches thus far.

Both models have Leverkusen top, as does the league table. Near the top, Werder Bremen are two spots higher when stats are taken into account. Bayern and Hamburg go the other way. The biggest movers overall were Mainz, who drop 5 places, and Stuttgart, who moved up 4 spots. While the stats model is still pretty new and I'm working on it, as a general rule the teams that are higher in that model than the goals-only one have usually gotten unlucky and run below expectation in goals given how their matches have gone. On the flip side, teams better in the goals-only ranking have been lucky and scored more goals than expected. I believe that the stats-based model is better when it comes to being predictive.

La Liga Rankings

Real Madrid picked up a big win at the Mestalla, otherwise it was as expected near the top. The biggest story is probably Pepe being out for the rest of the year for Real Madrid.

Here are the rankings using the system that only takes goals into account:


GFR - Goals for rank
GAR - Goals against rank
EGD - expected goals if they played a new season at the level shown by the scorelines thus far.

Here are the rankings going by the system that uses stats:



EP is the number of expected points if they played a new season at the level shown so far by the scores and stats from all the matches thus far. The big positive changes from the two rankings systems are Getafe and Zaragoza. Getafe are 4 spots higher in the system that uses stats and Zaragoza 6. Going the other way, when I included stats that dropped Sporting de Gijon 5 spots and Osasuna, Racing de Santander and Almeria all 4 spots. I'm still looking into the new stats model, but that's likely an indicator that Getafe and Zaragoza have been unlucky and run below expectation while Sporting, Osasuna, Racing and Almeria have run above expectation.