There is no manual, no template for international rugby captains and coaches but there is a strong trend with half of the top 10 sides at the World Cup led by loose forwards while another three have forward leaders.
The Wallabies and Pumas are led by hookers and lock Paul O'Connell captains Ireland with the Springboks and Scotland the only teams with backs as captains.
Jean de Villiers in the centre is the nominated Springbok captain while halfback Greig Laidlaw will lead the Scots.
The All Black model in recent years has developed into shared leadership where a senior group of players, spread across multiple positions, work on their areas of expertise to channel into Richie McCaw's captaincy. He once wrote there was no point in trying to be a captain if you were not worth your place in the side.
"Maybe once a century, someone in some sport defies the convention. England once had a cricket captain called Mike Brearley who was not the world's greatest opening bat but who had a mind like Plato. He was a successful leader.
"But don't try that at home," McCaw said. "I know from personal experience that first and foremost you have to be good enough to be out on the field in your own right and you have to be playing well. If you are struggling with your own game it makes it so much harder to smile and help others. I have been there."
England coach Stuart Lancaster is a disciple of the shared leadership philosophy.
"The captain as iconic leader is not how it works in rugby," he said.
"You have leaders across the field and our strength is in the collective. Chris [Robshaw] represents that collective and he does it brilliantly. We have told the players it is their team, so they need to push and drive it."
Maybe the pattern of forwards as captains amongst the top 10 nations has developed because seven are coached by former forwards with Steve Hansen (All Blacks), Joe Schmidt (Ireland) and Philippe St Andre (France) the only coaches who played in the backs.
In the list of the last 10 players who captained the All Blacks only Tana Umaga and Mils Muliaina played behind the pack. Out of the 10 All Blacks skippers before that, only three were backs.
The nation's three most decorated skippers have all been forwards. Current leader Richie McCaw has done the job an extraordinary 105 times, Sean Fitzpatrick led the side on 51 occasions and Wilson Whineray ran out 30 times at the head of his side.
Tana Umaga's stint as captain in 21 tests stands out as a rarity for someone who made his mark in midfield.
Six of the teams who have won the Webb Ellis Cup started those tournaments with forwards as their captains. Since 1991 Francois Pienaar, John Eales, Martin Johnson, John Smit and McCaw have lifted the trophy.
2015 RWC captains
(top 10 rated sides)
All Blacks Richie McCaw, flanker
Wallabies Stephen Moore, hooker
Ireland Paul O'Connell, lock
Springboks Jean de Villiers, centre
Wales Sam Warburton, flanker
England Chris Robshaw, flanker
France Thierry Dusautoir, flanker
Argentina Agustin Creevy, hooker
Fiji Alapusi Qera, flanker
Scotland Greig Laidlaw, halfback