The analysis of international rugby is laden with danger. Fixtures are infrequent (on average, Tier 1 nations have played fewer than 12 games per season across 2016 and 2017), yet the traditional depiction of test matches – imbued with a deep emotional resonance – lends itself to the inference of significant meaning from single data points. A loss by New Zealand in a test match is attributed with significance that a loss by Saracens in a Premiership game is not, because of the sparsely populated environment in which it stands. For another data point on a club or franchise, it may only be necessary to wait another seven days; months can pass between internationals. The degree of light which a single game can shed on the underlying abilities of the respective teams is the same in each scenario, but the difference in the first case is that an additional data point to confirm or deny a suspected trend is usually not far away; analysis can be measured and sceptical, knowing that in a short time a little more information will become available, rather than conclusive and emphatic.
Two years into a World Cup cycle there is sufficient information available to review the performance of each team, with Tier 1 nations having played between 20 and 29 test matches each. What follows is an attempt to establish not only which teams have been successful, but also the tactical approach which they have employed in order to be successful.