It’s been a great World Cup. When the tournament finally featured its first, inevitable stultifying 0-0 draw between Iran and Nigeria, many joked that finally, the actual World Cup had begun. In recent decades, the World Cup has featured defensive tactics and cagey games with few attackers making dangerous runs. In the first seventeen matches of the last World Cup, there were just 28 goals scored. Already Brazil 2014 has seen 49 goals.
What can the stats tell us about goal-scoring in Brazil? One important note, here, is that the “first seventeen matches” qualifier is somewhat misleading. While there were only about 1.5 goals per match in the first set of matches, the entire group stage produced a little over two goals per match. Scoring in Brazil is still up from South Africa, but by a somewhat smaller margin if we use the whole first round as the comparison set.
There have been, then, about 0.75 more goals per match scored overall in the group stages this year compared to 2010. The breakdown of the difference is notable. On goals scored from open play or set pieces, the increase has been relatively small, about 0.4 goals per match. But goals from penalties and own goals have nearly tripled, from about 0.19 per match all the way up to 0.53 per match. The occurrence of own goals in soccer matches is highly unpredictable, and that part of the equation should probably be chalked up to random variation.
Penalties are a little harder to figure. Most of the penalties at this year’s World Cup have not been as soft as the one awarded to Brazil in the opening match. It may be that the more attacking play at the Cup is producing more penalties. At the same time, you would not expect penalty awards to go up at a rate more than twice the rate of actual goal-scoring, if attacking play is the ultimate cause. It is also possible that we are seeing a referee effect in which referees are less passive about calling penalties when they occur. I have to suspect that random variation is the key driver of the increase in penalties as well as own goals, but it will be fun to watch.
I can also look at the goal scoring through another lens, that of expected goals. Has goal-scoring gone up because we’ve seen a rash of excellent finishing or poor goal-keeping? Or is the underlying cause simply more exciting games featuring more and better chances? Based on expected goals, the answer appears to be the latter. When people say that the World Cup has been more exciting this year, they are not just being misled by goals totals. The games have not only been high-scoring, they have also featured more exciting and creative attacks producing more and higher-quality goal attempts.
The stats confirm! A great World Cup!
Overall, expected goals have tracked goals scored almost perfectly in this tournament. South Africa 2010 featured, it seems, some poor finishing, excellent goal-keeping, or perhaps chance creation that was poorer than expected goals can pick out. Some fascinating recent research by Colin Trainor demonstrates that slow-paced attacks score at lower rates than fast-paced attacks, and so possibly the slower pace of World Cup matches impacted goal scoring in a way that location-based expected goals does not identify.
In the case of South Africa 2010, however, I think the evidence points more to random variation. In the first 17 matches in South Africa, goal-scoring was way down, but expected goals show a much smaller effect.
Those terribly low-scoring early matches in South Africa were not quite as poor for chance creation as the goals totals might indicate. When scoring picked up over the final 31 matches, and into the knockout rounds as well, a big part of the cause was most likely regression to the mean. Goals were coming, based on chance creation, and after a slow week they indeed appeared.
If 2010 is an indication, expected goals rates through the first period of matches appear to track goal-scoring rates in the following matches well. There may be fewer penalties and own goals, and thus lower overall tallies, but high rates of chance creation from open play hopefully can be maintained. The exciting attacking style that has characterized World Cup 2014 may continue throughout the tournament.
All data provided by Opta unless otherwise noted.
Michael Caley writes for Cartilage Free Captain, where he analyzes fancy soccer statistics and bemoans Tottenham Hotspur’s most recent failures. You can follow him on twitter at @MC_of_A. My full World Cup projections and methodology can be found at SB Nation.