Teams evolve. So it was that when the Grand Slammers of 2009, Brian O'Driscoll and Paul O'Connell et al, retired, it turned out not to be the end of the world, or even the end of Ireland as a major force. Their achievements assuredly contributed to the baton being passed on, but greatness had to emerge in their absence, and it has.
James Ryan and Garry Ringrose are exceptional international players, perhaps on the verge of greatness, while world-class players emerged elsewhere, not least at half-back.
Conor Murray and Johnny Sexton start their 50th Test together today against England, including two for the Lions. The Murray-Sexton halfback combination is the fourth most capped halfback pairing of all time, and fitness permitting, should overtake the Irish record of the celebrated Peter Stringer-Ronan O'Gara axis before the World Cup or certainly during it.
And that will be fine by O'Gara, who, besides which, will probably always have his record Irish and Munster points hauls.
To get to World Player of the Year is a true victory for hard work, perseverance and dedication
"It's great for me as I know the two guys," says O'Gara, back in Ireland as a pundit with Virgin Media for the opening two rounds. "I know the two people who go into the jerseys.
“Johnny is insanely competitive and driven. To get to World Player of the Year is a true victory for hard work, perseverance and dedication.
“I’d also put Conor in that category. I think either of the two half-backs could have easily won it, but they are in that category because of Team Ireland being so good. I don’t think it’s like a Messi or a Ronaldo in rugby. I think it’s a massive victory for Irish rugby along with team of the year and coach of the year, but either of the half-backs could have been chosen as World Player of the Year.”
Sexton made his debut in November 2009 against Fiji at the RDS and for the best part of two seasons was engaged in a ferocious battle, tinged with a Leinster-Munster edge, for the Irish number '10' with O'Gara, before Murray emerged first as a teammate of O'Gara's at Munster.
When Tony McGahan first propelled Murray out of the Munster academy and above both Stringer and Tomás O'Leary for the successful 2011 Magners League run-in, the province's then press officer, Pat Geraghty, vowed to this writer that Murray would make the Irish World Cup squad later that year.
When Murray was duly named by Declan Kidney as one of five scrumhalves in an expanded training squad, he still seemed fifth -choice behind O'Leary, Stringer, Eoin Reddan and Isaac Boss.
But all that changed when Murray made his Test debut off the bench in the second warm-up match against France in Bordeaux when replacing Eoin Reddan to partner O’Gara for the last 20 minutes.
On a hot, humid evening, Murray looked utterly unfazed and unflappable. It was like he was winning his 50th cap. Aside from having all the tools to be a Test match animal, Murray had the temperament.
“I think that’s what separates him. He’s the Federer,” says O’Gara of Murray. “I would be a little bit biased because he’s Munster. But he has a very pleasant way of getting the job done too. Even when he’s training hard, he’d have a little bead of sweat while the rest of us would have red heads. There’d be steam coming out of everywhere.”
"He used to call me Monty Burns from The Simpsons. I would be in the gym with him and he's powerful and he's strong. I'd be doing everything in my power to cheat and keep on a par with him."
A fortnight after that debut in Bordeaux, Murray won his second cap when he and Sexton came on together for the last 18 minutes of the World Cup warm-up defeat against England.
Their first start together was in the World Cup pool win over the USA on a sodden night in New Plymouth, but they weren't selected together again as a '9/10' until the following 2012 Six Nations opener against Wales at the Aviva, a 23-21 defeat.
Out of little acorns and all that.
There followed a 42-10 home win over Italy in tandem, and a 17-all, rescheduled draw away to France. In their first 12 Tests as a starting partnership, Ireland won just four games. In the next dozen they won ten. Today they will be seeking to make it 12 unbeaten.
Save for this season’s neck injury, Murray’s career has been a steady progression. As with the 2011 World Cup, he returned from the Lions’ tours of 2013 and 2017 a better player.
After the first Lions tour especially, under Rob Howley’s tutelage, Murray seemed to rid his game of taking a step or two before releasing the ball. Similarly, his phenomenal box kicking has also improved consistently over the years, along with his try-scoring rate and much else besides.
"That's what good coaching does," says O'Gara. "At the start Joe was a little 50-50, and was initially inclined to play his Leinster man, Eoin Reddan, on the Irish team, because Conor wasn't thinking anything like Joe wanted him to think in how he saw the game."
“He’s shaped him into the player he is. He’s made him the world’s best box kicker, and that’s the way rugby has gone.”
Since returning, Murray’s performances haven’t hit the exalted heights he set for himself previously, but it’s only a matter of time.
“At the minute I don’t think we’re seeing the consistently brilliant,” says O’Gara. “We’re seeing glimpses of it. But that’s only normal when you want him firing next October, and I’ve no doubt he will do that.”
Not unlike O'Gara himself, or indeed Eric Elwood and David Humphreys before him, Sexton has produced the best rugby of his life in his late 20s and 30s.
“When you think about it, that Leinster and Ireland season was amazing,” says O’Gara. “It must have been so rewarding. Johnny was the key driver of that. The challenge is to do it again, which is going to be very difficult, mentally and physically.
“But no better man to have a crack off it, from what I know of him. He’ll be leaving no stone unturned in his preparation. He loves it, and that’s what he lives for.”
With three Six Nations titles, including one Grand Slam, and a drawn Test series with the Lions in New Zealand already achieved, Murray and Sexton are the most decorated Irish halfback pairing ever in international rugby. They started all but one of the 15 Tests in Ireland's three title successes, and they started the second Test win and drawn third Test for the Lions.
You actually wouldn’t swap Murray and Sexton for any other halfback pairing in the world right now, and it’s doubtful you’d ever have said that about an Irish ‘9/10’ before.
“For nobody. For nobody,” says Brian O’Driscoll, before adding with a chuckle, “don’t get me wrong, [Aaron] Smith and [Beauden] Barrett are pretty tidy and there’s very little between those two combinations, but you’re dealing with the World Player of the Year last year and consistently either the best or the second best scrum-half of the last five or six years.”
As a pairing, Murray and Sexton also tick so many boxes, in their respective kicking, passing and running games, but also in their defensive work, and to that can now be added decision-making, experience and a well-oiled understanding.
Murray has got such a calmness. He's so unflappable. I think that's his greatest strength
"Murray has got such a calmness," says O'Driscoll, echoing O'Gara. "He's so unflappable. I think that's his greatest strength. In massively pressurised environments and situations, it feels like he's playing for Garryowen, and Johnny – even though he vents every so often – he has such an inner belief and such a will to achieve, it's remarkable.
“It’s testimony to his desire to get better after such a long career that he puts so much focus into his rugby. Lots of other players look at other things, but Johnny is an exceptional professional, about time, effort and diligence, and all the small things. I think he’s one of the best pros that I’ve ever seen.
“I think as well, what’s likeable about both of them is the humility. There’s no arrogance about them. With Johnny, genuinely every award that he picks up he’s not just saying ‘thanks a million, I feel so lucky.’ He really does. It really comes across that way and it’s nice to have your superstars that way.”
And, of course, they’re not finished yet.
Most capped halfback partnerships in Test history
78 Tests: George Gregan and Stephen Larkham (Australia)
53 Tests: Peter Stringer and Ronan O'Gara (Ireland).
52 Tests: Alessandro Troncon and Diego Dominguez (Italy).
49 Tests: Conor Murray and Johnny Sexton (Ireland) – Wins 31. Draws 3. Losses 15Conor Murray and Johnny Sexton's 49 tests as starting half-backs.
Sep 1st, 2011, World Cup, v USA, Won 22-10.
Feb 5th, 2012, 6N, v Wales (h) Lost 21-23.
Feb 25th, 2012, 6N v Italy (h), Won 42-10.
March 4th, 2012, 6N v France (a) Drew 17-17.
June 9th, 2012, v New Zealand (a) Lost 10-42.
June 16th, 2012, v New Zealand (a) Lost 19-22.
June 23rd, 2012, v New Zealand (a) Lost 0-60.
Nov 10th, 2012, v South Africa (h) Lost 12-16.
Nov 24th, 2012, v Argentina (h) Won 46-24.
Feb 2nd, 2013, 6N v Wales (a) Won 30-22.
Feb 10th, 2013, 6N v England (h) Lost 6-12.
Nov 24th, 2013, v New Zealand (h), Lost 22-24.
Feb 2nd, 2014, 6N v Scotland (h) Won 28-6.
Feb 8th, 2014, 6N v Wales (h) Won 26-3.
Feb 22nd, 2014, 6N v England (a) Lost 10-13.
March 8th, 2014, 6N v Italy (h) Won 46-7.
March 15th, 2014, 6N v Frfance (a) Won 22-20.
June 7th, 2014, v Argentina (a) Won 29-17.
Nov 8th, 2014, v South Africa (h) Won 29-15.
Nov 22nd, 2014, v Australia (h) Won 26-23.
Feb 14th, 2015, 6N v France (h) Won 18-11.
March 1st, 2015, 6N v England (h) Won 19-9.
March 14th, 2015, 6N v Wales (a) Lost 16-23.
March 21st, 2015, 6N v Scotland (a) Won 40-10.
Aug 29th, 2015, RWC warm-up v Wales (h) Lost 10-16.
Sept 5th, 2015, RWC warm-up v England (a) Lost 13-21.
Sept 19th, 2015, RWC v Canada, Won 50-7.
Oct 4th, 2015, RWC v Italy, Won 16-9.
Oct 11th, 2015, RWC v France Won 24-9.
Feb 7th, 2016, 6N v Wales (h) Drew 16-16.
Feb 13th, 2016, 6N v France (a) Lost 9-10.
Feb 27th, 2016, 6N v England (a) Lost 10-21.
March 12th, 2016, 6N v Italy (h) Won 58-15.
March 19th, 2016, 6N v Scotland (h) Won 35-25.
Nov 5th, 2016, v New Zealand Won 40-29.
Nov 19th, 2016, v New Zealand (h) Lost 9-21.
Feb 25th, 2017, 6N v France (h) Won 19-6.
March 10th, 2017, 6N v Wales (a) Lost 9-22.
July 1st, 2017, Lions v New Zealand (a) Won 24-21.
July 8th, 2017, Lions v New Zealand (a) Drew 15-15.
Nov 11th, 2017, v South Africa (h) Won 38-3.
Nov 25th, 2017, v Argentina (h) Won 28-19.
Feb 3rd, 2018, 6N v France (a) Won 15-13.
Feb 10th, 2018, 6N v Italy (h) Won 56-19.
Feb 24th, 2018, 6N v Wales (h) Won 37-27.
March 10th, 2018, 6N v Scotland (h) Won 28-8.
March 17th, 2018, 6N v England (a) Won 24-15.
June 16th, 2018, v Australia (a) Won 26-21.
June 23rd, 2018, v Australia (a) Won 20-16.