This is a bit complex, but let’s try. Here’s the key. When two international rugby teams meet, they play both for actual match score points (i.e. to determine who wins / loses / a draw), AND in turn, for international Rating Points. The latter is based on an exchange system. It has a number of ins and outs, but basically what Team A gains in Rating Points if it wins, Team B loses – i.e. it is a zero sum game, equivalent to an exchange between the teams.
A key nuance: during RWC, World Rugby doubles the normal Rating Points exchange calculated for each game. So an RWC win, for example, is basically worth double an equivalent Six Nations game, for Rating Points calculation purposes.
Why? Per WR, “…we have added a weighting for matches in the World Cup Finals, to recognise the unique importance and prestige of this event”.
So on to Wales and the previous world ranked number 2 Australia, who both won since the last update. How did Wales climb to second position in the updated rankings list? We haven’t done the specific maths, but the keys are that Australia gained almost no rating points from beating lower ranked Fiji, while Wales benefited from an away RWC win against a previously higher ranked England. So from a Welsh viewpoint, the normal gain from an away win against a higher ranked team was doubled, as it was an RWC game.
World Rugby periodically updates the Rankings, e.g. today Wales rose to #2, with 87.31 Rating Points. The rankings themselves are simply an ordered listing of the Rating Points scores, from highest to lowest. See the table below, New Zealand are ranked #1, with the highest number of Rating Points, and so on.
|Rank||Nation||Rating Points||On previous list|
|1||New Zealand||92,89||No change|
|Source: WR rankings as at 28th Sept 2015|
World Rugby’s own detailed rankings explanation is here.