They are always there, always contributing something, whether making that tackle when they have no right to be on their feet again, making a tough carry, protecting a player at the breakdown, just doing the gritty job of clearing away, supporting when others cannot get near the ball-carrier or just diving on a loose ball.
They are the players who allow the talent around them to shine. They link everything together. They always seem to make good calls.
While, say, Pocock and Hooper can hunt around the field in a pairing, Fardy has to be cuter, having to make more decisions in his reading of the game. After the first breakdown a six has to read where he has to go and who his next partner is, whether he is pairing up with a centre or a second row.
Both Fardy and Kaino were magnificent last weekend, even though Kaino was yellow-carded. In the first half when South Africa threw all their physicality at the All Blacks, it was often Kaino who was doing most to repel them.
And as for Fardy's contribution in the second half, when Argentina might have scored two or three tries against other team, well, he was quite unbelievable. He is even better now than he was when Australia beat New Zealand in Sydney last summer.
Away from the bigger names, watch closely if you can for Fardy and Kaino. You will certainly not be disappointed by how good they are or how hard they work.
- London Daily Telegraph
*Sir Ian McGeechan is a former Scotland and British and Irish Lions coach.