If you don't use a muscle repeatedly, eventually it begins to atrophy. It needs to be consistently tended to in order to grow and get bigger. Ireland's attacking muscle is tiny. The team may have made gains in other areas - their defence is excellent, their scrum is solid at full-health and they obviously have a strong kick-chase game.
But as the top international sides keep showing us, attack is what wins the biggest games. If you can't score tries - plural, not singular as it has been for Ireland recently - you won't come away with anything.
Let's call Ireland's current plight 'The Cian Healy Effect'.
Healy was once Ireland's most explosive ball carrier. He steamrolled defenders in the same manner that saw Billy Vunipola run so destructively today. But the memories of Healy causing damage fade with each subsequent performance.
The loosehead has bulked up to an impressive extent, but it is worth wondering whether he neglected the skills that made him so feared by spending so much time working on another area.
The same can be said of Ireland. In their quest to play a highly accurate game based on territory, ruck speed and kicking, have they been giving the necessary time to their attack?
Ireland have scored two tries in three Six Nations games. That is a terrible return. But what makes that stat even more frustrating is that they haven't been clinical AT ALL.
They had two or three chances to cross the line against France early on while they squandered about five good chances today through a combination of excellent English defence, poor finishing and sloppy play in the tight.
They lost three lineouts in England territory. Cian Healy was penalised at a key scrum in their 22. They weren't able to clear out a ruck soon after and England won a turnover penalty 25m out.
Before that, Robbie Henshaw was tackled superbly by the covering Jack Nowell when a try seemed certain.
In their only chance in the first half, Rory Best knocked on in English territory. After Ultan Dillane and Josh van der Flier combined beautifully in attack, Ireland were short of ruckers to blow Mike Brown away before he had a chance to dance on Conor Murray's face.
And while JVDF had a solid debut, he simply had to ground this ball when given such a good opportunity.
I suppose you could say that at least there was plenty created, unlike in the French performance, which becomes an increasingly embarrassing and unjustifiable loss after each matchday.
But the foundation that Joe Schmidt's Irish empire was built on - that buzzword of 'accuracy'- has been sorely missing once the team crosses into the opposition 22.
There is very little creativity around the try-line - it is no surprise that Ireland's two tries have been two-yard Conor Murray snipes since Ireland's attacks when within 5m are just a series of one-out runners.
There were some positives today. The debutantes were strong while Johnny Sexton showed huge testicular fortitude to play the way he did after all the shit surrounding him during the week.
But it shows how entrenched Schmidt is with his kick-chase style that he opted to keep Andrew Trimble on the field when Ireland badly needed a score instead of Stuart McCloskey, who was finally coming into the game in attack. The Ulster wing was clearly shattered and could barely do more than jog for the last 20 minutes.
The hallmark of Ireland's back-to-back Six Nations wins was their ability to strike clinically when chances presented itself.
Three games into this Six Nations, it looks like that ability has waned and unless Ireland rediscover their sharpness, they will be a long way off beating anybody other than Scotland or Italy.