Murray wary of Big Billy's power
The selection of Care and Youngs indicates Jones's search for tempo
Conor Murray knows all about the umbilical link that connects forwards to backs.
When it comes to the set-piece scrum, the relationship between Ireland's eight, Jamie Heaslip, and nine is one that has been honed over time.
The threats of the various world-class number eights around the world are varied.
Italy captain Sergio Parisse is a ball player who can grind it out or offload with the best of them.
New All Black captain Kieran Read is an athlete with uncommon skills.
Wales's Toby Faletau is an all-round workhorse. Heaslip is what they like to call a players' player, one willing to sacrifice for others.
Billy Vunipola is a different animal altogether and resembles, in one huge frame, the traditional power base of English rugby.
"He is right up there in terms of ball-carrying," said Murray.
"I found that out last year in the Aviva when he picked off the back of the scrum. I didn't concentrate on tackling him and he made a big bust up the field.
"If I am on the pitch against him this year, I have to pay close attention to him especially off the base of the scrum and that is just my area."
Where Stuart Lancaster instilled the belief of extolling the virtues of team-first, his successor Eddie Jones is more about embracing the X-Factor of the individual.
"In terms of open-field running, he (Vunipola) is right up there as a ball carrier," continued Murray.
"He always seems to break the first tackle. He is willing to switch the ball from one hand to the other and in the offload he is a handful."
Perhaps the best personal performance of Vunipola's career came when he single-handedly destroyed Munster in the Champions Cup last season.
The England international led the way in carries, tackles, metres made, offloads and defenders beaten to end the Irish province's qualification ambitions.
"Munster know that and I know that from playing against him," admitted Murray.
"He is definitely a player that gets forward momentum.
"He is a challenge among a number of challenges."
In terms of scrum-half, Lancaster appeared to favour more fundamental skills of Saracens's Richard Wigglesworth to complement Ben Youngs or Danny Care.
Jones has sent out the message, through selection, that he wants to go to high tempo straight away and keep it going all the way to the 80th minute.
When Vunipola establishes the front-foot, there are few quicker to take advantage of space on the fringes than Care and Youngs.
Care has put troubled times behind him away from the game to rediscover his love of the sport.
"He is well capable of playing a structured game," said Murray.
"He got the start against Scotland and that was a tight match, where things had to be more structured because conditions were not that good.
"He has a structured game and can direct a pack around the place."
Jones handed Youngs the number nine shirt against Italy in what could well be viewed as a chance for each to show who should start against Ireland.
"Both of them can make good breaks," said the Ireland half-back.
"We play against these guys quite regularly and know them quite well.
"We are going to have to make sure our knowledge is up to scratch and be ready for them."
In a game that is so pre-rehearsed and structured, the greatest openings can come out of the unexpected.
This can come from a creative scripted move, individual brilliance or from bad play.
Looking back, it seemed somehow appropriate that a mediocre France undid Ireland with a sloppy set-piece.
It was something similar to the crabbing scrum that left Wales's Faletau with no option other than to pick and place from another five-metre scrum.
Ireland have twice been thwarted by scrum mistakes made by the opposition.
"It's hard to plan for something like that," said Murray.
"Our five-metre scrum defence is in a good place and we know what we're doing there."
If Ireland cannot control the scrum so close to their line, England have the twin threat of a lively scrum-half or giant carrier to make them pay the same price three times on the trot.