The truth of that is seen almost every June when the All Blacks come out of Super Rugby and then, usually, struggle in their opening test as they come to grips with the different requirements.
The collision pretty much determines everything in test rugby. Win the physical encounters and it sets up everything else. No side wins much if they can't generate momentum, which is not so much the case in Super Rugby.
The last non-New Zealand winner of Super Rugby were the Reds in 2011. They were intuitive and creative, went well up front and had Will Genia and Quade Cooper pulling the strings. They beat the Crusaders in the final but, when many of the same players swapped into All Black and Wallaby jerseys later in the year, New Zealand were triumphant.
The 20-6 semifinal defeat of the Wallabies was the best All Blacks performance at the last World Cup and it was a victory built on twin pillars of excellence: their dominance in all the contact areas and their ability to neutralise the Wallabies' kicking game.
The Waratahs are well coached, organised and, in Israel Folau, have one of the best strike weapons going. They'd be worthy champions but none of this, merely by extension, makes the Wallabies a potentially dominant force.
Super Rugby may be telling one story but, by the end of the respective June tests, a different picture was becoming clear. New Zealand and South Africa look to be the two best-equipped sides to challenge for the Rugby Championship.
The Wallabies have qualities, such as Folau, the consistency of Adam Ashley-Cooper and the dynamism of Michael Hooper. Give them an inch, and all that...
But that's really the problem for the Wallabies. How are they are going to win that inch? The All Black pack came out of the three tests against England well ahead. If they replicate that intensity and accuracy, Australia could be toast - burnt toast, as their pack, while improved and more robust perhaps than previous years, still doesn't appear to have that collective menace.
A Waratahs title would boost the confidence of some key players but it won't give the Wallabies a devastating scrum or thumping presence at the tackled ball.
It's possibly not too far from a flip of a coin when it comes to South Africa. The margin between them and the All Blacks is small. Even if the All Blacks deliver, they might not win. The Boks do the important parts of test rugby well - really well - and a couple of epic encounters await.
But the Boks run the risk of being out on their feet by the end of the tournament. Their policy of selecting offshore players has the capacity to derail them.
It's probable their European-based players will have to turn out for their clubs in the international bye weeks and Springboks coach Heyneke Meyer was already concerned about fatigue after his side's second June test.
"I'm really worried about the state of my players," Meyer said after South Africa's late 32-31 escape against Wales. "I don't want to make excuses but I've never seen the players so tired at this time of the year."
