Two years on from the Twickenham scrum implosion that arguably confirmed the erasure of Declan Kidney's dwindling authority as Ireland coach, the pack that returns there this weekend is upholstered by formidable strength in depth.
Like a butterfly flapping its wings in the Amazon, we'll never know had the IRB allowed a second tight-head prop the right to sit on the replacements' bench in 2012 whether Ireland may have suffered so grievously.
When an injured Mike Ross trudged from the rain-soaked SW London turf, Ireland's scrum accelerated backwards at a rate of knots.
In effect, even before Ulster's Tom Court, primarily a loosehead, arrived to put out the fire, Ireland's house was already crashing down around their ears amidst an inferno of furious onslaught from the England eight.
"In 2012, we got beaten up there to put it mildly and it cost us the game," noted Rory Best grimly yesterday.
A penalty try, six scrum penalties and three scrums against the head contributed to all but three of England's points in the 30-9 drubbing; Ross returns this weekend but he will not be alone in shouldering the weight of the world, or even the Ireland scrum, on his prominent north Cork shoulders.
As Stuart Lancaster yesterday contemplated the loss of his tighthead, Dan Cole, to a bulging disc for the remainder of the campaign, he mused that Ireland would be in similar difficulties if they lost Ross for this week's renewal.
The evidence suggests that his is a wholly incorrect assessment. Best politely offered a counterpoint after briefly recalling 2012.
"We had a starting loosehead to come in and stop a scrum going backwards," Best observed. "It wasn't fair on him, he was scapegoated. We weren't good as an eight that day.
"We've seen enough from Marty Moore that he is more than adequate to come on and do a job. Our bench has shown impact and we know we're going to do that again."
That Moore is justifiably seen as a viable contender to even usurp Ross at some stage this season demonstrates just how the tables have turned.
That Ireland's reserve front-row so comfortably finished the opening two Six Nations ties, combining for nearly a half-hour all told, is a remarkable shift in faith in Ireland's reserve strength.
In contrast, the palpable anxiety in England's camp yesterday at the prospect of losing the over-worked and indispensable Cole, who has played every game under Lancaster – barring an absence on Lions duty – was obvious.
That his replacement, David Wilson, is deemed a lightweight replacement remained unspoken but Lancaster's comments demonstrated a stark contrast to Ireland's current strength in depth in this area.
"He has proved his fitness in a Premiership game," declared Lancaster when asked was he convinced if Bath's Wilson could step up to the mark, before adding unconvincingly, "In an ideal world I'd like to give him more game time or integrate him from the bench, but we're not in an ideal situation."
"We haven't got a whole load of tightheads of his experience in the Premiership," he added.
"The two Saxons ones: Will Collier's injured and Paul Doran-Jones is just getting back playing having had a neck injury himself.
"Then if you keep going down the list, Scott Wilson is 19. Kieran Brookes is probably the one who, for me at the weekend, put his hand up the most playing for Newcastle. And he came on for the Saxons as well."
None of these would match the reserve strength demonstrated by Moore's remarkable rise with Ireland though, and England cannot afford to risk the stability of their set-piece.
"Not really," remarked Lancaster. "You wouldn't put David in if you felt he couldn't get back up to speed. But he's intelligent he's been round the England camp for such a long time.
"He's played in the autumn internationals, he started against Argentina. While he's been injured it's not like he's not been conditioning or whatever.
"It's just hard sometimes when you come back and play on a heavy pitch against Exeter when they're running the ball around left, right and centre. That's what he found challenging more than anything else."
Insecurity riddled yesterday's England briefing, compared to the calm that existed in Carton House, with much of the chat focused on the conversion of rugby league star Sam Burgess to a future in England's midfield.
The immediate foundations are of deeper concern, though.
"It's probably the one area where we've got least depth," Lancaster bemoaned. "At hooker for example, whilst Rob Webber is now injured, David Paice is back playing for Irish and good young players coming through. Loosehead and second-row likewise.
"But there are a few specialist positions and tighthead is one of them. I don't think I'm different from any other coach in any other country to be honest.
"If Mike Ross fell down for Ireland, or Adam Jones for Wales or Nicolas Mas for France, those coaches would be thinking the same thing. It's a specialist position and it's a shame we've lost him."
Such was the concern, the temptation was put to him that perhaps Joe Marler or Alex Corbisiero could be switched across.
"No," Lancaster said abruptly. "Whilst they have had some game time at tighthead it's been mainly in their development."
Which is where we came in, really. Ireland are formidably stacked in the front-row this weekend; it is England who now crave their opponents' stability.
"This Irish scrum has evolved a lot," concludes Best.
"It's going to be another massive test on Saturday and that will show just how much it has evolved.
"It's certainly a challenge you're looking forward to.
"You ask any front-row and they'll tell you if you scrum well, you finish well on the scoreboard."
At the very least, the figures will look far better than they did two years ago.