One of the most interesting elements of the Rugby Championship which kicked off yesterday is the burgeoning competition in, and the changing role of, that most New Zealand of all positions - the openside flanker or No7.
Rugby in recent years has changed so much and so quickly that it is often difficult to keep up with it all. Perhaps that is most true of the openside flanker's role.
This year's four-nations clash will line up Richie McCaw and Sam Cane against the Wallabies' David Pocock, Michael Hooper and Liam Gill and South Africa's Marcell Coetzee, plus Pumas bruisers such as Juan Manuel Leguizamo.
What's clear is that the traditional role of a No 7, while still applicable, has other requirements added these days.
It is no longer enough to be the team's pre-eminent tackler and first to the tackled ball; a stealer of possession. These days, the 7 has to be able to do all that - and carry the ball and be an effective support player.
All Black skipper McCaw has clearly built that into his play in recent times. In last year's World Cup and the three recent tests against the Irish, he was probably the All Blacks' most prominent ball-carrier.
Many will remember former All Black No 7 Josh Kronfeld during the World Cup saying Australia's David Pocock had edged ahead of McCaw.
That was almost certainly an assessment based on steals, where Pocock has been hugely effective in recent times. But it likely does not take into account the changes the evergreen McCaw has built into his game - using that astonishing 'engine' of his to power his work as a ball-carrier and link man. Pocock, on the form available before the Rugby Championship began, was nowhere near that level in those areas.
Cane, the young All Black who performed so creditably against Ireland, had a reputation as a skilled ball winner in the rucks and mauls - but made a greater impression as a link man and runner against Ireland.
The role is evolving. The Australians have included three openside loose forwards in their TRC squad: Pocock, Hooper of the Brumbies and young Gill, of the Reds. It's led to some speculation that they may, at times, play two 7s instead of the more usual openside plus a ball-running blindside.
Certainly Hooper fits the bill and is second choice to Pocock. A talented ball-grubber, he is also capable of running with the ball through crowded areas. He has a penchant for scoring tries in Super Rugby when close to the line.
South Africa have almost always favoured the ball-running, spoiling loose forward and the highly capable Coetzee has kept renowned ball-fetcher Heinrich Brussow out of the Springbok side, even when Brussow has not been injured.
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Perhaps Gill best illustrates the changing role of the 7, or will do so. Many opensides (for example, McCaw) are now being used as lineout options and Gill has a future in that phase.
The 20-year-old openside flanker, signed by the Reds when he was 17, played a game-winning hand in their defeat of the champion Chiefs during the Super Rugby pool phase. What was ultimately gob-smacking about his performance was its sheer maturity and his almost flawless technique at pilfering ball in that horrible, messy duck soup of a thing called a ruck.
Against the Chiefs, Gill arrived at the breakdown, timed his entry perfectly and robbed ball. He has the uncanny ability of remaining on his feet even as the clear-outs rain in. Five times he stole ball as the Chiefs pressed hard, raids that might normally return points.
It is impossible to overstate the importance of such turnovers in the modern game, built as it is around continuity and multiple phases to overcome sophisticated and wide-ranging defensive screens. Gill didn't quite win the game on his own but he certainly blew out the Chiefs' flame as they were about to run hot.
One of the great Australian No 7s, Simon Poidevin, said of Gill after the match against the Chiefs: "He was absolutely outstanding and I think the hardest markers of any No 7s are New Zealand sides - they test them like no one else."
However, Gill has yet to make the grade in terms of tackle count and ball-carrying. It was also noticeable that he - like any foraging flanker can be - was taken out of the game almost totally when the Reds played the Sharks later and the South African pack blew the Reds out of the breakdown. That's the reason for building more facets into the all-round play of the No 7. Rugby has few places for the out-and-out specialist these days.
Gill doesn't have those dimensions yet but many judges are predicting that, when he has filled out a little more and become a bit more experienced, he could be one of the most dangerous 7s. He made one blistering run against the Chiefs that day - a reminder of his days as a sevens specialist in the Australian international side.
All Black coach Steve Hansen, who has begun planning for the future (McCaw is 32 this year) said of Cane: "I think he could be something special. He is big, robust, great over the ball and plays an intelligent game. He is a fetcher, he can get over the ball, he can carry and he defends well."
If that's so, we have some mouth-watering rugby treats in store in coming years. Cane vs Hooper or Gill (or possibly Hooper and Gill) looms as one of those ongoing clashes over which all sports fans salivate.
None are big men and are of roughly similar dimensions. Gill is 1.85m and 94kg, Hooper 1.82m and 97kg, Cane is 1.89m and 103kg, Pocock 1.84m and 104kg, and McCaw 1.87m and 106kg. But all have speed, technique and unflagging engines. Perhaps McCaw - still - and Kieran Read have the most impressive motors of any loose forwards in the game yet but ... change is coming.
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There is perhaps no other position in rugby that says 'New Zealand' as much as No 7. The All Blacks have had a production machine over the years, just as the Welsh regularly produced world-class first five-eighths in eras past.
Not even South Africa, a place with a rugby history as fierce and passionate as our own, has produced as many leading 7s - think Kel Tremain, Waka Nathan, Graham Mourie, Michael Jones, Kronfeld and McCaw. Tremain the try-scorer; Nathan the constructive/destructive flanker who liked to run with the ball; Mourie perhaps the first really scientific openside, blessed not so much with pace but an unerring radar and ability to make the right decisions. Jones was the best ball-player, supporting runner and the most devastating tackler of them all and Kronfeld was perhaps the first to master the modern game and its emphasis on turnovers as well as support play, even if the game he played was a more open affair than that played today.
Perhaps the 1977 series against the Lions stands as the most compelling evidence - outplayed and out-muscled up front, the All Blacks won that series only because of the strength and depth of loose forwards such as Mourie, Kevin Eveleigh, Ian Kirkpatrick and Laurie Knight.
About 35 years on, the All Blacks continue to rely heavily on their loose forwards. The TRC will tell us whether the role of the 7 is changing more and whether New Zealand exponents will continue to be in the vanguard.