A former England centre, Will Greenwood, tells the funniest story I've ever heard about a blindside flanker, usually big, powerful, unforgiving, men who pack on the short side of a scrum.
Greenwood was playing a famously brutal test at Twickenham against South Africa in 2002, when the Springbok flanker, their captain Corne Krige, appeared to have worked out an English call being made for Greenwood to run from the openside to the blind at a scrum.
"Hey Greenwood," called Krige. "Run my side and I'll rip your head off and eat it."
Greenwood blanched. He appealed to the referee, Kiwi Paddy O'Brien. "Did you hear what he said?" O'Brien replied. "I did." "So what," Greenwood asked, "have you got to say about it?"
Replied O'Brien, "If I was you I wouldn't run the blind."
It's advice that from the time the magnificent Jerome Kaino settled into the No 6 jersey in 2008, and dominated at two World Cups in 2011 and 2015, players from all over the world would have been wise to follow when they played New Zealand.
In Newcastle, when the All Blacks met Tonga in their last pool game of the 2015 Cup, the press seats at St James' Park were right by the sideline. Early in the match a big Tongan forward got the ball with time to wind up and charge. His grievous error was that the defender he lined up was Kaino. Fifteen metres away on the press bench the smack we heard as the run came to a juddering halt was like the soundtrack to a "Rocky" movie.
Kaino himself never liked the idea of himself as the hardman in the All Blacks. "It's not how my family would see me," he told me in a radio interview in 2011, "and it's certainly not how I see myself."
Be that as it may, I'm with the a "Spasifik" magazine blogger, who, after Kaino had legally, but physically, reduced the superb Wallaby forager David Pocock to basically being a spectator in the 2011 Cup semifinal at Eden Park won 20-6 by the All Blacks, "Jerome Kaino and Superman once fought each other on a bet. The loser had to wear his underwear outside his pants."
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As the World Cup in Japan starts to loom, I'd suggest that finding a blindside flanker to replace Kaino is a more pressing task for the All Black selectors than working out what to do without Damian McKenzie, or how to juggle the back three, fullback and wingers, combination.
Kaino came from a long line of hard core, flint edged blindsiders, going right back to the 1950s, and Stan "Tiny" Hill (who recently turned 92), an Army staff-sergeant, who Colin Meads swore was the only man who ever scared him on a rugby field.
The template was cemented in the 1980s by Mark "Cowboy" Shaw, famous for seeking out new All Blacks and asking them in private, "Are you prepared to piss blood for this [All Black] jersey?"
Given his image, and aversion to interviews, during his career, it was a real surprise to me when, in the 1990s, I was hired to speak at a function at a Lower Hutt engineering firm where Shaw was the manager, and met the man rather than the rugby persona. Far from being gruff and monosyllabic, he was terrific company, personable and highly likeable.
Having had a tiny look behind the on-field mask, his laconic rugby mantra no longer felt macho, just the unvarnished truth. "I never hit a back," he's said, "and I never kicked anyone. Everyone I ever punched deserved it."
As the current selectors consider their options for blindside I'm sure their deliberations will extend well beyond considering who is the No 6 you'd least like to be trapped in a phone box with for a winner takes all showdown. Not all great All Black blindsides have been like cage fighters in footy boots.
The 1987 World Cup saw the emergence of the astounding Michael Jones, whose brilliance on the openside tended to overshadow another great player, his fellow flanker, AJ Whetton.
Whetton's own typically self-effacing take on how rugged he was is that he claims he "floated like a butterfly, stung like a butterfly".
What he did offer was massive, unfailing, commitment, and terrific athleticism. How agile was he, and how quick were his reflexes? Soon after John Adshead was the All Whites coach at the 1982 World Cup, Adshead organised a charity football game between a team studded with All Whites, and players from the Auckland rugby team, which was then basically the All Blacks.
AJ Whetton towered over even the bigger All Whites like Sam Malcolmson, and he weighed in at 100kg. Not exactly the first man you'd expect lynx-like reactions from.
Before the game started Whetton was given a workout as a goal keeper. The first All White stepped up to the penalty spot, and fired a blistering shot to Whetton's right. Whetton flung himself parallel to the ground and flicked the ball safely away outside the goal post. "Bloody hell," Adshead muttered to me. "Did that really happen?"
As the All Black selectors sift through the current crop of loose forwards, the hugely gifted Scott Barrett might be a long shot. As a specialist lock he is, of course, very big, he's extremely fast, and he's a worker, but if there was one question about him as a flanker it might be how nimble he is.
Possibly the only selection mistake John Hart made as he built the brilliant Auckland team of the 1980s, 10 of whom would play in the All Black side that won the '87 World Cup final, was in 1983 when he played Buck Shelford, a force of nature at No8, as a flanker in a Ranfurly Shield challenge against Canterbury.
Shelford would give a brick wall a run for its money if he ran at it, but twinkle-toed lateral movement wasn't his forte.
A decade after the game in '83, I was told by Wayne Smith, at first-five and backline general for Canterbury that day, how startled he was when Canterbury coach Alex Wyllie grabbed his arm in the tunnel at Lancaster Park as the teams were about to run out and said, "Run it from everywhere".
Halfback Bruce Deans got the message, and a series of searing breaks he made down Shelford's side of the scrum helped Canterbury to a stunning 31-9 victory. The following year, when Auckland belted Canterbury 32-3 at Eden Park, Shelford was firmly ensconced at No8, and AJ Whetton was on the blindside.
Now, one of the more interesting, if left field, candidates for the All Black No 6 jersey might be Luke Whitelock, who plays on the side of the scrum this weekend for the Highlanders, rather than at No 8.
Whitelock shows hints of both Whetton's huge work rate and unflashy, but extensive, skill set, in how he goes about his business. There's also the fact the selectors know exactly how he fits with the group, having first picked him in an All Black squad way back in 2013.
There are, of course, specialist blindsiders too. If Liam Squire's knee injury allows him time to regain top form he must be a leading contender, while Shannon Frizell and Vaea Fifita are certainly rugged enough. A fit Squire might have the jump though on the grounds of experience, with 23 tests since 2016, compared to Frizell's four last year, and Fifita's nine since 2017.
If Sam Cane's recovery from his horrendous neck injury is complete, there might be thoughts given to moving him to 6, and playing Ardie Savea at 7. Having a lineout specialist in the All Black loose trio can be left to Kieran Read, one of the safest pairs of lineout hands in world rugby.
Will the loose forwards of 2019 be as stunning as the combination of Read, Richie McCaw, and Kaino was in 2015? Highly unlikely, as in '15 all three were the best in the world in their positions. Should we be nerve wracked about that fact? Not really. Why not? Because the biggest threat after the domination of 2015 was surely the All Blacks becoming complacent. A little anxiety over the back three, and the loose forwards, might not be a bad thing as the tournament in Japan approaches.