The Best Bet for RWC 2019
Ireland will face the winner or runner up of Pool B. That will be either New Zealand or South Africa depending on which order they finish. It's likely to be England/Wales or Australia in the semi final. Then for the Final one of those five again - whichever they have managed to avoid so far. It will require beating the caliber of the Top 6 in the world, not just once, but THREE times consecutively.
So what should be Ireland's expectation? How has their win rate been in the past versus this standard of opposition? Including the 2015 RWC and all matches since Ireland have played these teams 22 times (6 vs WAL, 5 vs ENG, 4 vs SA, 4 vs AUS, 3 vs NZ) and winning 12 times. That's about a 55% win rate. If Ireland have won 55% of past meetings, then they could expect to win 55% of future meetings. This is the same as saying they have a 55% chance of winning a single once off match. So 3-in-a-row? The Maths would say 55% x 55% x 55% = 17%. So that's it. That is the probability that Ireland will win the Rugby World Cup (based on only a few assumptions and past results).
This estimate comes with several warnings:
1. Small Sample. 22 matches doesn't give us enough information to form a decent long run average that we can be confident with.
2. Irrelevant Matches. In this sample some matches were friendlies, with weaker squads. This sort of information won't inform how a full strength Irish squad would perform against a full strength All Black's squad with a World Cup at stake.
3. Squad Churn. Definitely related to the above point is squad churn. Are matches played with a different squad 4 years ago going to tell us much about how the current squad will perform. For Ireland only 39% of the squad named for RWC2019 were named in RWC2015, so that is 61% of that squad gone and irrelevant.
4. Form. This process has somehow estimated Ireland's long term strength. But form comes and goes, from the high of last year winning the Six Nations and beating the All Blacks, Ireland are now in a position where they have had an average Six Nations and a some times humiliating warm up to the World Cup. Is their form right now more relevant than their overall ability?
5. Draw. People will point to the draw as being unfortunate for Ireland with one of the BIG Southern Hemisphere teams in wait in the quarter finals. This is true, however Scotland are one of the less fancied teams so it gives Ireland a real chance to win the Pool and avoid the All Blacks. In any case to win the RWC you will have to play the best eventually. I am not sure that we can point to the draw as a particular reason to dampen enthusiasm.
6. Stage Fright. Ireland have never been able to bring it for the biggest competition in the World. Going out tamely to Argentina in 2015 and Wales in 2011. They have never made it past the Quarter Finals. This could also be a criticism directed at other teams though - even England recent winners were eliminated at the POOL Stage last time. And NZ, undeniably the best team in the world only won 1 of the first 6 World Cups. NZ have corrected that now holding 3 from 8 tournaments - but if you considered the 1 from 6 anything other than bad luck/variance when pricing up the 2011 competition you would have been caught out.
With all these caveats I have repeated the process for all 6 teams that are top in the Outright Market. I have added the betting market prices too for comparison.
There are huge discrepancies - for all the reasons pointed out above. So it remains a decision whether you think the reasons are all valid enough or weighty enough as to negate what looks like great value on Ireland or some of the other teams.
England are an interesting proposition though, as opposed to Ireland they are actually coming in to the World Cup with some good form, and the draw has been good to them. Firstly there are none of the other Big Six in their Pool. Secondly Australia (the least fancied of the Big Southern Hemisphere sides) or Wales (the least fancied of the Big Northern Hemisphere sides) will be waiting in the Quarter Finals. The squad has also seen less turnover with only 52% missing from the previous campaign.
South Africa are also quite interesting. Now of course their number produced with this basic approach will be hurt by playing NZ more often than the Northern Hemisphere teams meet them. However even discounting for that and adjusting I still can't find a reason in their past record that elevates them to 2nd Favourites. In the period in question they have only won 42% of their matches vs AUS, 50% vs IRL and 40% vs ENG, and they haven't beaten Wales in the 4 attempts since their win in the 2015 World Cup Quarter Final.
In conclusion, the naive approach to estimating the probabilities has not been very accurate at all when compared to the market odds. It does highlight some prices though which are difficult to justify, in my opinion.
So what should be Ireland's expectation? How has their win rate been in the past versus this standard of opposition? Including the 2015 RWC and all matches since Ireland have played these teams 22 times (6 vs WAL, 5 vs ENG, 4 vs SA, 4 vs AUS, 3 vs NZ) and winning 12 times. That's about a 55% win rate. If Ireland have won 55% of past meetings, then they could expect to win 55% of future meetings. This is the same as saying they have a 55% chance of winning a single once off match. So 3-in-a-row? The Maths would say 55% x 55% x 55% = 17%. So that's it. That is the probability that Ireland will win the Rugby World Cup (based on only a few assumptions and past results).
This estimate comes with several warnings:
1. Small Sample. 22 matches doesn't give us enough information to form a decent long run average that we can be confident with.
2. Irrelevant Matches. In this sample some matches were friendlies, with weaker squads. This sort of information won't inform how a full strength Irish squad would perform against a full strength All Black's squad with a World Cup at stake.
3. Squad Churn. Definitely related to the above point is squad churn. Are matches played with a different squad 4 years ago going to tell us much about how the current squad will perform. For Ireland only 39% of the squad named for RWC2019 were named in RWC2015, so that is 61% of that squad gone and irrelevant.
4. Form. This process has somehow estimated Ireland's long term strength. But form comes and goes, from the high of last year winning the Six Nations and beating the All Blacks, Ireland are now in a position where they have had an average Six Nations and a some times humiliating warm up to the World Cup. Is their form right now more relevant than their overall ability?
5. Draw. People will point to the draw as being unfortunate for Ireland with one of the BIG Southern Hemisphere teams in wait in the quarter finals. This is true, however Scotland are one of the less fancied teams so it gives Ireland a real chance to win the Pool and avoid the All Blacks. In any case to win the RWC you will have to play the best eventually. I am not sure that we can point to the draw as a particular reason to dampen enthusiasm.
6. Stage Fright. Ireland have never been able to bring it for the biggest competition in the World. Going out tamely to Argentina in 2015 and Wales in 2011. They have never made it past the Quarter Finals. This could also be a criticism directed at other teams though - even England recent winners were eliminated at the POOL Stage last time. And NZ, undeniably the best team in the world only won 1 of the first 6 World Cups. NZ have corrected that now holding 3 from 8 tournaments - but if you considered the 1 from 6 anything other than bad luck/variance when pricing up the 2011 competition you would have been caught out.
With all these caveats I have repeated the process for all 6 teams that are top in the Outright Market. I have added the betting market prices too for comparison.
| P | W | D | L | P[W] | P[WWW] | Dec Odds | Matchbook Odds | Squad Churn | |
| NZ | 28 | 22 | 1 | 5 | 78.57% | 48.51% | 2.06 | 2.52 | 66% |
| ENG | 25 | 17 | 0 | 8 | 68.00% | 31.44% | 3.18 | 5.90 | 52% |
| IRL | 22 | 12 | 1 | 9 | 54.55% | 16.23% | 6.16 | 12.50 | 61% |
| WAL | 26 | 9 | 1 | 16 | 34.62% | 4.15% | 24.11 | 15.50 | 65% |
| AUS | 34 | 8 | 2 | 24 | 23.53% | 1.30% | 76.77 | 19.00 | 61% |
| SA | 29 | 9 | 3 | 18 | 31.03% | 2.99% | 33.46 | 5.40 | 55% |
Table: Big 6 Head to Head records. Including RWC2015 to present.
There are huge discrepancies - for all the reasons pointed out above. So it remains a decision whether you think the reasons are all valid enough or weighty enough as to negate what looks like great value on Ireland or some of the other teams.
England are an interesting proposition though, as opposed to Ireland they are actually coming in to the World Cup with some good form, and the draw has been good to them. Firstly there are none of the other Big Six in their Pool. Secondly Australia (the least fancied of the Big Southern Hemisphere sides) or Wales (the least fancied of the Big Northern Hemisphere sides) will be waiting in the Quarter Finals. The squad has also seen less turnover with only 52% missing from the previous campaign.
South Africa are also quite interesting. Now of course their number produced with this basic approach will be hurt by playing NZ more often than the Northern Hemisphere teams meet them. However even discounting for that and adjusting I still can't find a reason in their past record that elevates them to 2nd Favourites. In the period in question they have only won 42% of their matches vs AUS, 50% vs IRL and 40% vs ENG, and they haven't beaten Wales in the 4 attempts since their win in the 2015 World Cup Quarter Final.
In conclusion, the naive approach to estimating the probabilities has not been very accurate at all when compared to the market odds. It does highlight some prices though which are difficult to justify, in my opinion.
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