Now that September has drawn to a close, we can take an interesting look back at what has been a great Rugby World Cup tournament so far. There has been close encounters and shock results, as well as dominant displays by impressive teams. Here we explore the impact these results have had on the rankings and the extra insight that can be drawn from this.
September Ranking Picture and Movers
There has been some movement in the ranking table since the World Cup began with some interesting stories around the changes. Twelve of the twenty teams have experienced no change to their ranking position, including the top three ranked sides of New Zealand, England and Ireland. But it is still early days…
The first move occurred after Wales beat Georgia 43 – 13 on September 23rd to step up into 4th in the rankings swapping position with South Africa. South Africa regained the 4th spot just five days later by comfortably beating Namibia 57-3. This ranking triumph was short lived as Wales’ 29-25 victory over Australia the following day put them into 4th in the rankings again.
Lower down in the table, the ranking journey of Uruguay and the teams around them has been one of intrigue. Results of world cup conspired in a way that meant they lost a ranking place to Canada on September 24th before either team had even played a tournament match.
The following day they rectified this, in spades, as they played the game of their lives to defeat Fiji 30 – 27 []. This result meant they not only [NL1] overtook Canada but Tonga as well to move into 16th place in the ranking. Their final major act in September was to lose to Georgia 33 – 7 on September 29th which returned them to their original starting position, of the World Cup, of 17th.
The final teams to be major drivers in ranking changes were the USA and Samoa. The USA lost 48 – 7 to England on September 26th and this cost them two ranking places from 12th to 14th in the ranking.
But, before the month was up the USA regained a place and moved into 13th as Samoa lost to Scotland 34 – 0 on the final day of the month.
Italy gained a place during this time, although their performances against lower ranked opponents of Canada and Namibia were, by margins, very close to what the ranking model would expect, and therefore their rank gain has been as a result of the teams around them (namely the USA and Samoa) losing by larger margins than expected.
Ranking Score Movers
Looking at the ranking scores over time provides some extra insight into why there hasn’t been rank changes for some teams, but there has nevertheless been progression and regression for some teams.
What better place to start than with the three clear favorites for the tournament, New Zealand, England and Ireland.
Both New Zealand and England have performed well this tournament with impressive victories and built on their ranking scores. New Zealand’s has increased by from 18.3 to 18.7 and England’s from 15.4 to 15.9. Ireland’s World Cup has already taken some twists and turns, epitomised by their impressive victory over Scotland that saw their ranking score raise from 13.5 to 13.9, followed by their shock defeat to Japan which meant they finished the month on a ranking score of 13.2. Whether New Zealand and England continue to make progress, and if Ireland produce impressive future results, is yet to be seen, this will be played out over next few weeks.
The positions from 4th to 6th in the rankings are the most hotly contested and there has already been movement. Wales, South Africa and Australia have all shown themselves to be impressive teams and capable of not only creating an interesting ranking narrative, but also taking the trophy home.
Positions 7 through 11 appear more stratified for now, although there are chances for changes with Scotland in 7th, getting closer to Australia in 6th and Japan in 11th making ground on Fiji in 10th. Naturally, there will need to be more impressive performances to force change but who knows what might be possible in this World Cup?
On the face of it, the bottom nine teams appear closer together than top 11, however a closer look reveals there are clusters of teams and battles for ranking points occurring within this group. In particular: Italy, the USA and Samoa have been battling it out between themselves and Uruguay have proved to be a ranking disruptor amongst the bottom five teams.
Septembers Biggest Shock Result
There were two matches in September which are obvious candidates for the shock result of the tournament. They are Uruguay’s 30 – 27 victory over Fiji and Japan’s 19 – 12 victory over Ireland.
Both of which were victories for a lower ranked nation, and both remarkably, involved a team predicted to finish not one, but two, places below the team they beat if the rankings are used as a predictor or final position in each Pool. Both results have been vitalising for the competition, but which one was judged to be the more surprising by using our ranking model?
The first piece of evidence to weigh up is to look at the relative ranks. Uruguay went into their match ranked 18th against Fiji’s 10th, and Japan went in at 11th versus Ireland being the 3rd ranked team. Therefore, both underdogs achieved victories against sides ranked eight positions above them.
As the difference between ranks is clearly not consistent through the table, to explore this further we need to consider the relative ranking scores of the teams. Going into the matches, Uruguay had a ranking score of 0.3 to Fiji’s 3.3, and Japan had a ranking score of 2.0 compared with Ireland’s 13.8.
Clearly the difference is larger in the Japan vs Ireland game, however using these values in a simple calculation it is possible to create pre-match probabilities of each underdog scoring a victory in the match. Before the match Uruguay were judged to have an 8% chance of scoring the victory and Japan’s probability was modeled to be 13%.
So, Uruguay’s result was the biggest shock, but is it that simple? Not if you are to consider the margin of victory in each game. Uruguay’s 30-27 result was clearly closer fought than Japan’s 19-12, and our modelling calculates Uruguay to have 56% dominance and in this encounter. Japan on the other hand are modelled to have 69% dominance. Taking the margin of victory into consideration, now supports Japan’s case for being the biggest shock in September.
Both matches significantly shock up the ranking table but did so in slightly different ways. The obvious benefactors of the shock results were Uruguay and Japan who added 0.5 and 0.4 to their ranking score respectively.
Uruguay gained two places in the table to 16th, but Japan remained in 11th place. Fiji lost 0.2 points from their ranking score and Ireland 0.7. So, the absolute ranking score changes were bigger after the Japan vs Ireland game, but the relative change is bigger after the Uruguay vs Fiji game. The overall ranking table experienced a total of 1.4 ranking score points being redistributed after the Uruguay vs Fiji game, and a total of 2.0 ranking score points being redistributed after the Japan vs Ireland game.
So, by considering the output from the ranking model the conclusion is that it is difficult to tell which of the two big shocks was the biggest of the Rugby World Cup. Both results were special in their own way, but if I had to choose I would have to go with the result and impact of the host nation Japan achieving a victory over one of the favorites for the tournament in Ireland, and the impact this could have on the outcome of Pool A and indeed the remainder of the competition.