They used to talk about the spine of a side. No doubt rugby-speak has produced a different description these days but the principal remains – any successful team needs a strong spine, that is the backbone formed through hooker, No 8, half-backs and full-back.
Stuart Lancaster, England's head coach, must be delighted to see that the first and last of those positions have been all but nailed down. Mike Brown followed up last Saturday's man-of-the-match display against Australia with a consistent showing here against an Argentina side that never genuinely threatened England's line.
At the other end of the spine, Lancaster can pick either Dylan Hartley or Tom Youngs against New Zealand next weekend and feel confident. Youngs has held down the hooker's jersey nearly all year and enjoyed success against the All Blacks last December but he will be feeling Hartley's hot breath on his neck.
This was only Hartley's second start in the last 18 months, the hiatus caused by injury and indiscipline, but remember that he was Lancaster's captain against South Africa in the third international of the 2012 tour. He threw well to the line-out yesterday and he was explosive in broken play, picking some delightful lines on which to make inroads.
Would that matters were clearer in the centre of the spine. There is no doubt that Owen Farrell is the preferred choice at fly-half but the scrum-half/No 8 link has still to be forged and that is crucial. Lancaster has a problem at scrum-half: Lee Dickson has been rewarded for his club form this season – yesterday there was a strong Northampton element running through the more successful aspects of England's game – but he was wheeled off far too smartly to suggest that he will start against New Zealand.
"I thought Lee did what we wanted in terms of tempo, bringing pace and intensity to the game," Lancaster said. So why not leave him longer than 52 minutes? Dickson had prospered behind an ample supply of ball in the first half without really stamping his authority on the game but the true test of any player is performance in adversity and, in the second half, England's possession dried up alarmingly.
So Danny Care, England's most experienced scrum-half, was given something of an ambulance job when he replaced Dickson. Care had to scurry hither and yon making tackles, rather than having a stable platform off which to attack so Ben Youngs, the third strand in this selection conundrum, may have felt quietly pleased that he was nursing a bruised hip which kept him off the bench.
Lancaster expects Youngs to be available for selection this week and, given the Leicester man's up-beat display as a replacement against Australia nine days ago and his portfolio of experience which is almost as great as Care's in England terms and could be considered greater given that he has a Lions tour under his belt, he must be considered ahead of Dickson.
But so much revolves around the No 9 that the whole side needs to know who is top of the pile, for the sake of individual and collective confidence. Not one of the nines available has been able to play his way into international form while the position of No 8 is no foregone conclusion – a situation that, obviously, impacts on the scrum-half.
There was no more delighted individual at Twickenham yesterday than Ben Morgan when he burst his way through three feeble tackles and scored England's fourth try. Morgan has struggled at club level with Gloucester this season and was affected by injury during the 2013 RBS Six Nations but, on his day, he is a defence-breaking forward.
Conversely, Billy Vunipola is finding his way at this level. This month Vunipola celebrated his 21st birthday and his raw strength and talent is there for all to see; he made an excellent impression on his first start against Australia but the big, physical Pumas were well prepared and Vunipola was gone before the hour mark.
Not too much should be read into this, for Morgan is one of too many England players who need game time. But Lancaster will have in mind that when England run out next Saturday, their preferred No 8 will be facing the best in the world in Kieran Read. That demands much of either Morgan or Vunipola: form and fitness suggest the younger man should start while Morgan, who played against the All Blacks a year ago, may bring greater maturity.
Either way, the All Blacks will look at England's spine and consider that here lies a weakness. There is no better nation for exploring and exposing a fault line, and New Zealand have had a year to digest the bile raised by losing 38-21 at Twickenham. They do not forgive easily.
Alphonsi's dream return in revenge victory
England's women made it a double success at Twickenham as they gained revenge on France with a comprehensive 40-20 victory in a game played immediately after the men had beaten Argentina yesterday.
In February England lost at Twickenham for the first time when France beat them 30-20 in the Six Nations.
But yesterday the home side dominated from the start and put next year's World Cup hosts to the sword with six tries against just two for the French.
Kay Wilson crossed twice to add to scores from Claire Allan, the stand-in captain Katy McLean, Ruth Laybourn.
There was also a dream try for Maggie Alphonsi as she made her long-awaited return to rugby after a lengthy spell out injured.
England now head to the Stoop on Wednesday to face World Cup opponents Canada.