I’m frequently at Tootsie’s, an Italian restaurant and cafe at the Stanford Barn with amazing food. When I asked the owner Rocco about Italy before the start of Euro 2012, he said, “We suck”. After Italy tied Spain in the first game, he proclaimed, “We’re going to win Euro.” When I told him Italy had a 36% chance to advance over Germany in the semifinals, he kicked me out. Well, no, but Rocco reflects the optimism of Italy as they face Spain in the final fixture of Euro 2012. The Power Rank gives Italy a 37% to win Euro 2012 over Spain.
Let’s break this down further, shall we?
What assumptions go into this win probability?
This prediction involve three steps. First, we use our core algorithm to rank the offense and defense of each country. Second, we employ these rankings to generate goal rates for Spain against Italy and vice versa. Third, we plug these goal rates into a model to get a score, both at the end of regular time and over time. In this model, we assume the goals scored by each team are independent of each other.
Well, the goals for two teams in a match are not independent. If they were, we would find that the correlation coefficient between the goals for the home and away teams in Euro qualifying is zero. It’s not. The correlation coefficient is -0.26. This implies that if one team scores a lot of goals, the other team tends to score fewer goals. The Wikipedia page for correlation coefficient has some nice pictures of what a plot of home versus away goals might look like.
From a soccer perspective, this negative correlation coefficient could mean that teams play more defensively when they take a lead. With match details beyond the final score, one could determine if goals rates are different based on the score. If so, that suggests a better probabilistic model for the final score than the independent Poisson random variables we use now.
If the game goes to penalty kicks, we flip a coin. Spain and Italy would then have a 50% chance to win Euro 2012. This model seems consistent with popular opinion, as an ESPN commentator has talked about the complete randomness of penalty kicks. Moreover, it’s difficult to imagine a better model since there is such little penalty kick data for each player.
Will Spain score against Italy?
In our rankings, Spain has the 4th best offense in the world. We predict they would score 2.16 goals against an average defense. However, this goal rate probably depends on who plays up top. When Ferrando Torres enters the game, the Spanish game transitions from a crisp passing game to an offense interrupted by offsides penalties on Torres. Spain plays much better with Cesc Fabregas at this attacking position.
Our ranking have Italy as the 25th defense in the world, despite giving up only 0.71 goals in meaningful competition since the start of World Cup 2010 qualifying. Our methods predict they would concede 0.79 goals to an average offense. However, Italy’s rating might suffer from weak competition in European qualifying matches. You can’t concede less than 0 goals to the Faroe Islands, the 107th best offense in the world. Italy’s defense features 3 defenders from a Juventus team that allowed only 0.53 goals per game in Serie A.
Will Italy score on Spain?
While Mario Balotelli has received most of the attention after his 2 goals against Germany, play maker Riccardo Montolivo is the key to this Italian offense. He made the pass found Balotelli behind the German defense for his second goal. Moreover, Montolivo made a number of incredible passes against England that led to missed goals for the Italians. Italy has the 17th best offense, predicted to score 1.76 goals against average international competition.
However, they face a stout Spainish defense, 3rd best in the world with a 0.44 rating. The Spanish haven’t conceded a goal since Italy’s Antonio Di Natale scored in the first match of Euro 2012. While known for their short passing game, Spain has a defense that has played a huge role in their Euro 2008 and World Cup 2010 victories. Can Sergio Ramos, the Val Kilmer of soccer, lead a defense that wins a historic Euro, World Cup, Euro triple crown?
What do you think?
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