COMMENT
As with the conclusion of any major test tournament, World Cup predictions abound.
This one may not go down well in Wales.
Warren Gatland's men are worthy Six Nations champions. They deserve to sit second in the world rankings after defying England and Ireland in Cardiff to claim the treasured grand slam crown. No one can take away that achievement.
Suggesting they should now be short-priced World Cup contenders requires a leap of faith, though.
From this observation point, England are the All Blacks' greatest northern threat.
How quickly that has altered, too. Four months ago Ireland were unstoppable.
Elevating England might sound strange, given the mental fragility Eddie Jones openly documented after their second half capitulation against Scotland at Twickenham.
Their inability to handle pressure will likely spark more 4am texts from Jones to management.
When assessing the threat to the All Blacks, though, potential is probably most important at this juncture.
For all their issues and form fluctuations, England produced the most commanding, compelling performance of the Six Nations.
By travelling to Dublin on opening weekend, and ending Ireland's 12-match unbeaten home run, England revealed their true potential.
Some may point to Wales' shutout of Ireland in the final round as a performance to rival but glance ahead to the hard and fast tracks Japan promises, and England's effort in Dublin was much more foreboding.
At those levels of commitment and ruthless conviction, England should be the Northern Hemisphere's World Cup flag bearers.
Of course, with Pumas coach Mario Ledesma outlining plans to select Argentina's overseas-based stars for the World Cup, England could just as easily crumble out in the pool.
For now, let's assume they progress.
When Maro Itoje and Mako Vunipola are fit, England's forwards are second only to the All Blacks in terms of dynamism. This element sets them apart in Europe.
England's power and precision blew Ireland away. In truth Joe Schmidt's men - the toast of the world so recently - are still reeling from the nature of that beating; the confidence of playmakers Johnny Sexton and Conor Murray so rocked they have not recovered.
In openside Tom Curry and centre Henry Slade, England boast players of quality and balance. Collectively, England are developing attacking variety. The second half against Scotland aside, their defence has improved dramatically, too.
England scored 24 tries in this tournament. Their fondness for bullying lesser teams bloats that figure, with eight coming against Italy. But they still amassed 14 more than Wales, though Gatland's men did accumulate the second most points (70 behind England).
The strength of Wales' Six Nations success instead lies in their ball retention and Shaun Edwards-inspired defence. They conceded seven tries and an average of 13 points per game, prompting Scotland coach Gregor Townsend to label it the best defence in the world.
There is also, without doubt, growing belief attached to 14 test wins in a row.
It would, however, be naïve to believe quality opposition won't manage more than 13 points in Japan.
Perhaps more than any other rugby nation, Wales rise on emotion. And it is here questions begin to arise.
There is a big difference between contesting a grand slam at the Principality Stadium, in the pouring rain, on a sodden pitch, with almost 80,000 chanting locals, compared to a pool match in Japan.
While the tide turned somewhat with the unbeaten run in November, Gatland's record with Wales against the Springboks, Wallabies and All Blacks – seven wins from 41 tests since 2007 – also lingers.
The Southern Hemisphere adopts different tactics and styles and, so, when considering the World Cup, analysis must be broadened well beyond a Six Nations context alone.
How much have Wales progressed since their last 33-18 defeat to a weakened All Blacks team, missing Brodie Retallick, Kieran Read and Ben Smith among others, in Cardiff in November, 2017?
This is not to say Wales are not capable of giving the World Cup a proper shake. Add influential No 8 Taulupe Faletau back in the mix, and their back-row has real strength.
Perspective is, however, needed when it comes to global permutations, given Wales have not faced the All Blacks in almost two years, and the contrasting conditions Japan will bring.
Scotland, with the magic touch of Finn Russell pulling the strings, could yet be the surprise package if they can get their best team on the park.
The final word must be on Ireland – their regression this year quite stunning.
Four of five matches were well below standards.
In his post-match address from Cardiff, following the worst performance of his tenure after the request for the roof to remain open backfired, Schmidt turned on his media by suggesting preparation was undermined by publishing the team early.
Never mind Ireland were held scoreless for 82 minutes and seemingly bereft of ideas when forced to chase the game.
Angst is again rising, with suggestions Ireland's gameplan is broken and that opposition have identified they simply need to match them physically.
The truth probably is somewhere in between.
Ireland's attacking game is in need of most attention, with Schmidt's convictions now to be seriously tested.
Predictions are made to be broken but, on the evidence of this Six Nations, England at their peak could cause the All Blacks the most problems.
The missing rugby jersey was found after a two-year search.