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Opinion
While New Zealand and Ireland are the most likely sides to win the 2023 Rugby World Cup, a final between these two powerhouses is unlikely.
The most likely final will be between the Pool A members France and New Zealand (13.1%), followed by Pool B members, South Africa and Ireland (10.7%), and then South Africa and New Zealand (6.7%).
These results come from a “Monte Carlo” simulation developed for the RWC 2023. The model considers the historical outcomes from head-on-head encounters between teams, the relative ratings of the respective teams adjusted for recent form, and the impact of the draw.
Monte Carlo simulations are a powerful uncertainty modelling technique that calculates the chance of any particular outcome occurring instead of trying to consider every possible outcome in a complex system.
This technique was used in the development of the atomic bomb. I have tested the accuracy of the model with associated probabilities against actual outcomes from previous World Cups and recent Test matches. Although these probability assessments are subjective, they are based on solid evidence, good reasoning, and not a “gut feel” or what I would like to be true.
I found the model to be well-calibrated and will continue to refine the model as the year progresses.
Jerome Kaino of the All Blacks (Photo by Phil Walter/Getty Images)
The rugby equivalent of an atomic bomb was dropped when World Rugby decided to base the draw on the January 2020 World Rugby rankings.
At that stage, South Africa, New Zealand, England, and Wales were the top-rated teams that “headed” each pool (called Band 1).
What World Rugby couldn’t foresee was the dramatic rise of Ireland and France from position 5 and 7 respectively to the top of the table and the implosion of England and Wales to position 6 and 9 respectively. Considering today’s ratings, the top five teams (Ireland, France, New Zealand, South Africa, and Scotland) are on the same side of the tournament destined to eliminate each other.
The teams that manage to win Quarterfinal 2 and Quarterfinal 4 between Pool A and Pool B on the second weekend of October are considered very likely to progress to the final on the 28th of October.
The host, France, is considered by many as the favourite – this is not supported by the model. Unfortunately, we humans, have not evolved an intuitive ability to accurately assess probabilities for uncertain and complex systems such as the Rugby World Cup tournament.
Research shows that we are very bad at judging odds, suffering from a long list of irrational biases and heuristics. Any uncertain and complex system also produces non-intuitive outcomes that models can help us to clarify. The RWC 2023 model does not disappoint…
I have calculated the odds of each team progressing to the knock-out finals, the final, and the odds of winning the tournament. A table will be the best way to communicate this work, however as the format doesn’t allow me to include a table, I will list a few insights:
New Zealand (28.7%) and Ireland (23.6%) have the highest probability to win the tournament, followed by France (14.8%) and then South Africa (13.2%).
Although England (10%) and Australia (6%) suffered from poor recent form, they have the benefit of a draw that allows them to avoid at least two of the top five teams on their way to the final. They are however less likely to win the final against one of the top four battle-hardened teams.
The biggest loser of the draw is Scotland: Although Scotland is ranked 5th today, they are grouped in Pool B with Ireland and South Africa.
Even if they survive the “Pool of Death”, they will need to beat either France or New Zealand in the Quarterfinals. As Scotland has a poor head-on-head track record against the top four teams, the model calculates only a remote probability that Scotland progress past the quarterfinals.
The biggest winners are England, Australia and Wales. Despite their poor recent form, England and Australia still have a one-in-five chance to reach the final. It will be critical for these teams to end up on top of their pool as England is 7.5 times more likely to make the final if they win Pool D and Australia is 2.5 times more likely to make the final by winning Pool C. It will be less likely to reach the final if they are the Runner-Up.
What is far less intuitive, is that it doesn’t matter if New Zealand or France top Pool A as their path to the final are very likely to be similar. The best outcome for both Ireland and South Africa is if Ireland tops Pool B and South Africa ends up second.
There is potential for the top four teams to play the percentages and “game the system” or to rest players during the pool stages in preparation for the “make-or-break quarterfinals”. This is surely not what World Rugby wants to see in their flagship tournament.
In the next article, I will review what World Rugby can do to improve the integrity of the tournament and increase the odds that the best teams will meet in the final. They can consider changing the composition of the pools or the structure of the quarterfinals (more doable) or whatever options you think I should consider.
(Photo by David Rogers/Getty Images)
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