Partizan Belgrad vs Tottenham Hotspur

Tottemham has the better starting XI, but due to the home field advantage Partizan is expected to win.

Partizan: 46.9%
Draw: 29.4%
Tottenham Hotspur: 23.8%


PlayerGoalimpactPeak GIAgeLast National TeamNo. GamesNo. Minutes
Miroslav Vulicevic125.9132.929.319217479
Vojislav Stankovic118.0120.826.9998175
Milan Lukac111.0116.128.91059707
Lazar Cirkovic93.7105.822.0Serbien [U21]504269
Nikola Drincic87.094.630.0Montenegro21018261
Vladimir Volkov116.4122.528.3Montenegro1179461
Danilo Pantic88.1134.617.8Serbien [U19]21774
Branko Ilic96.8118.031.6Slowenien1078684
Petar Grbic102.1102.326.1Montenegro633536
Danko Lazovic112.0130.931.3Serbien34921788
Saša Ilic88.6151.236.7Serbien35024348
Filip Kljaji?86.3118.324.1585334
Andrija Živkovi?101.0146.418.2Serbien [U19]382583
Nemanja Petrovi?105.4116.222.3Serbien [U21]181323
Nikola Ninkovi?105.6132.919.7Serbien [U21]743918
Ismael Fofana102.4102.426.0231381
Predrag Luka105.0105.826.314310397
Saša Markovi?106.1112.623.5Serbien [U21]1197826

Tottenham Hotspur

PlayerGoalimpactPeak GIAgeLast National TeamNo. GamesNo. Minutes
Ben Davies96.9112.921.3Wales978409
Federico Fazio112.6116.927.5Argentinien Olymp.20816927
Kyle Naughton107.1107.525.8England [U21]22118966
Aaron Lennon113.5117.527.4England40729857
Jan Vertonghen143.6147.627.3Belgien35231315
Hugo Lloris124.0130.427.7Frankreich38435541
Harry Kane102.4119.921.1England [U21]1106335
Andros Townsend96.9104.723.2England15810437
Nabil Bentaleb94.5121.119.8Algerien362653
Benjamin Stambouli96.8101.224.1Frankreich [U21]1249186
Étienne Capoue110.7111.126.2Frankreich21318317
Erik Lamela95.1105.422.5Argentinien1309618
Vlad Chiriches116.9119.624.8Rumänien15413386
Christian Eriksen128.5138.622.6Dänemark21216421
Eric Dier104.0124.320.7England [U21]594589
Michel Vorm110.1113.230.8Niederlande27024769

Europa League: Recap Quater Finals

The 2013 Europa League quarter finals ended with huge surprises. The utter outsider Basel won over the top-favorite on the title, Tottenham Hotspur. The surprise quarterfinalist Fenerbahce defeated the high-rated team of Lazio.

Obviously, not everything is skill and luck is a large portion of the actual results. But is it really all that a surprise have the semifinalist that we now see? I would say 'no', because the prediction of Goalimpact was actually quite different than those of the bettting odds. After the round of last sixteen, I predicted the following results. Teams predicted to advance are marked green.

SL Benfica120,3106,8Newcastle United
121,2112,7Lazio Roma
Tottenham Hotspur121,2116,5FC Basel
Chelsea FC134,1113,5Rubin Kazan

And I concluded
So actually all pair consist of a clear favorite. The closest call is Spurs vs. Basel according to Goalimpact, however it is a clear win for the Spurs according to the Betfair odds.
All favorites did advance but Tottenham Hotspur. This game was predicted as a clear-cut victory beyond any doubt for Tottenham by the betting markets and as a tied tie with some advantage for the Spurs by Goalimpact. As the rematch went to the penalties, I conclude that calling this draw and a narrow decision is fair and thus Goalimpact's prediction seems to be closer to the actual outcome.

The other deviation between betting odds and Goalimpact's prediction was
Goalimpact considers Fenerbahce to be the favorite in the duel with Lazio while the odds see Lazio in front.
According to the odds, Lazio was three times as likely to win the title as Fenerbahce. According to Goalimpact, Lazio would need luck to even defeat Fenerbahce and advance to the next round. Given the gameplay in both legs, I think it is fair to say that Fenerbahce earned the victory. This was not a lucky punch of an underdog and thus a good call of Goalimpact, too.

Predictions sorted by Goalimpact
Chelsea FC134,125,9%
Tottenham Hotspur121,226,2%
SL Benfica120,317,5%
FC Basel116,52,7%
Rubin Kazan113,55,8%
Lazio Roma112,711,4%
Newcastle United106,86,5%

Predictions sorted by Betfair odds

Tottenham Hotspur121,226,2%
Chelsea FC134,125,9%
SL Benfica120,317,5%
Lazio Roma112,711,4%
Newcastle United106,86,5%
Rubin Kazan113,55,8%
FC Basel116,52,7%

The story the betting markets tell us, is that the tournament lost its best team, the Spurs, and the expected semifinalist Lazio and sees the two utter underdogs Fenerbahce and Basel advance by pure chance. The story Goalimpact tells is, that alle the favorites won their duels and only the close tie between the 3rd and the 5th ranked team ended in a minor surprise that the 5th ranked team advanced.

But I made one bad call, too.
The closest call is Spurs vs. Basel according to Goalimpact, however it is a clear win for the Spurs according to the Betfair odds. I personally tend to agree with the odds here.
The lesson to learn from this: Trust the data more than your prejudices.

Europa League: Recap Last Sixteen

Another round has been played in the Europa League. Time to check how the teams' Goalimpact fared as predictor for the rounds outcome. In the following table the advancing teams are marked green. The values given are the respective Goalimpacts as of 1st of March 2013.

Rubin Kazan113,5:106,3Levante UD
Zenit St. Petersburg123,5:116,5FC Basel
Inter119,1:121,2Tottenham Hotspur
Fenerbahçe121,2:117,9Viktoria Plzen
Girondins Bordeaux109,3:120,3SL Benfica
Newcastle United106,8:118,9Anzhi Makhachkala
Lazio Roma112,7:112,1VfB Stuttgart
Chelsea FC134,1:104,9Steaua Bucuresti

Out of the eight duels only in two the team with the lower Goalimpact won. Newcastle's defeat of the 12.1 points higher valued Makhachkala was the biggest surprise. The other was the defeat of Zenit by Basel. That said, in this round some of the decisions were extremely close. Most notably the narrow win of the Spurs over Inter, which was a very open duel according to Goalimpact anyway.

On average, the winners had a 4.28 Goalimpact of the losers. This underlines the predictive power of the algorithm. It the second round of the Europa League this was a lower 1.43, so among the last sixteen there were less surprises.

Of the remaining teams Goalimpact sees the following order.

Team Goalimpact Betfair Odds
Chelsea FC 134,1 25,9%
Tottenham Hotspur 121,2 26,2%
Fenerbahce 121,2 3,9%
SL Benfica 120,3 17,5%
FC Basel 116,5 2,7%
Rubin Kazan 113,5 5,8%
Lazio Roma 112,7 11,4%
Newcastle United 106,8 6,5%

We shouldn't expect the odds and the Goalimpact to be fully aligned, because the Goalimpact order doesn't account for the fixtures of the quarter finals. However, there are still one notable difference. Goalimpact considers Fenerbahce to be the favorite in the duel with Lazio while the odds see Lazio in front.

The predictions for the quarter finals are

SL Benfica 120,3 106,8 Newcastle United
Fenerbahce 121,2 112,7 Lazio Roma
Tottenham Hotspur 121,2 116,5 FC Basel
Chelsea FC 134,1 113,5 Rubin Kazan

So actually all pair consist of a clear favorite. The closest call is Spurs vs. Basel according to Goalimpact, however it is a clear win for the Spurs according to the Betfair odds. I personally tend to agree with the odds here.

Theo Walcott vs. Gareth Bale

There is some discussions going on whether Theo Walcott or Gareth Bale is the better player. @benjaminpugsley put an interesting blog post online where he neatly compares various statistics of both players. His conclusion is
Bale exhibits dominance over Walcott in every category.
So, according to a bottom-up view, Bale is clearly the better player. That said, as always bottom-up numbers are difficult to interpret. No complete model of football exists and therefore it is not obvious for each statistic if actually a high or a low number is good. Sometimes the answer is "it depends". In Benjamin's analysis, for example, a high ratio of a player's goals over the team's total goals is seen as positive as one interpretation is that he is a main contributor to the team's success. However, an alternative explanation is that the player cannibalizes goals that team mates could score, too. He maybe only seeks many shots and thus takes opportunities from the team mates. A third interpretation is that the passes he receives are so good that any player could score. So while he does a good job in scoring, he could be easily replaced with a team mate without the number of scored goals changing dramatically.

I have no idea which of the three explanations is the correct one. It could even be a mixture of them or some more other reasoning can be found. This is a general problem of the bottom-up approach. It delivers valuable insight and we can learn a lot, but it is hard to base a player comparison on it because we are sure to miss something.

So let's see what Goalimpact says to those two players. Goalimpact simply measures the player’s team’s goal difference when the player is on the field. It doesn’t look at how he effects his team’s goal difference. The value is corrected for other influences on the team's goal difference to increase accuracy
  • the players alongside him
  • the strength of the opponent
  • whether he has home advantage
  • red cards shown to either side
  • luck
The value is transformed into a human readable scale where 100 is the average over all players and the best player in the world has 190. In terms of Goalimpact, Walcott is superior to Bale by a rather big margin. Walcott has a Goalimpact of 141.5 and Bale only of 117.8. Both are well above the average of 100 and would be valuable contributors to every Premier League team. If we compare the development of their Goalimpacts and those of their team mates over time, we get the following chart.

As we can see, both are above their team averages. This indicates that the teams, on average, play less successful without them than they do when these players are on the field. However, the distance to the team average is much larger in Walcott's case. Bale's team seems to compensate his absence rather well as the distance is only 3.9 points. They play only marginally worse without him. For some time in 2011 the performance with and without him was even equal. In stark contrast, the Goalimpact of Walcott is 13.6 points higher than that of his team mates. If he is not playing, the team will have a hard time to compensate it and, on average, they are not managing it to full extend. The average goal difference without Walcott worse than with him.


Top-down sees Walcott as better than Bale. The disadvantage of bottom-up is that we can't really tell which player is superior and the disadvantage of top-down is, we have no clue why Walcott is better than Bale. Maybe he is working more for defense. Maybe Bale is cannibalizing goals from his team mates. Maybe something completely different.