Six months from now, an army of experts might cite Dublin's defeat to Tyrone as the watershed moment, the wake-up call, in their 'Drive for Five'. Or maybe those same pundits will nod sagely and recall March 16 as the first definitive sign that the empire was crumbling.
Results, dear boy, results: Dublin may be in the strange scenario of Allianz League also-rans ahead of Sunday's trek to Cavan, but All-Ireland destiny is still in their own gift.
They are the best team - the most talented and experienced and, thus far, driven.
But that doesn't mean they can't be caught, just as they were by a hungrier and more pinpoint and tactically savvy Tyrone on Saturday night.
When Cormac Costello pressed on the accelerator and then went for the jugular, all seemed well with the world. Perhaps that fourth minute goal came too early ... yet it was no impediment to a collective masterclass when Con O'Callaghan struck his semi-final thunderbolt at almost the exact same juncture in 2017.
Then, Tyrone had no answer ... whereas three nights ago they came with a plan and weren't remotely knocked out of their stride.
Just as well for Dublin that it was 'only the league' ... but the case for their defence of Sam has been weakened, even a smidgen, by the success of Tyrone's template.
More specifically, their defence is in the dock following Tyrone's persistent use of fast, accurate, often diagonal foot passes to one of their inside raiders - in the majority of cases either Cathal McShane or Mattie Donnelly.
The great irony is that both McShane and Donnelly are converted inside forwards, having spent much of their inter-county careers as denizens of the middle-eight battleground. Yet Mickey Harte appreciated this season that he needed to shake up their attacking game-plan, to utilise more powerful ball-winners closer to goal.
For Tyrone, this represents a pretty radical tactical shift. It was also the perfect weapon against a full-back line that found itself isolated, one on one, on numerous occasions.
The Dublin defenders under greatest pressure were Jonny Cooper (tracking Donnelly in the first half) and to an even greater extent David Byrne (who suffered in McShane's slipstream). Cooper is Dublin's go-to marker and invariably is in the zone when it counts. Byrne is only three matches back after a lengthy injury lay-off; he needs more game-time.
But, leaving aside individual form graphs, a bigger issue is the way teams have identified Dublin's full-back line as an area to exploit.
Monaghan shot 0-3 in offensive marks while both of their goals originated from marks that were run, pouncing on a fatal half-second of hesitation in Dublin's last line.
A fortnight later, Kerry tallied 1-11 of their 1-18 haul via open play. They were noticeably keen to test Dublin's aerial mettle; Steven O'Brien's goal originated in the modh díreach approach; Roscommon's goal in round five also resulted from a speculative Garryowen.
The good news for Dublin? The experimental rules won't be there come summer, so teams cannot use the mark as a weapon of choice. That's not to say they won't probe for weaknesses in the air: a tactic that led to goals for Galway and Tyrone (from a penalty) at the business end of last season.
The other good news? Presumably Jack McCaffrey will be back to rip up the turf as the ground hardens; the cutting edge he provides from deep was badly missed against Tyrone.
But it's in the defensive fundamentals that Dublin need to up their game. Cian O'Sullivan, the glue that binds this defence, didn't have his finest hour but James McCarthy was perhaps even more out-of-sorts. Discipline has been John Small's biggest issue but he has also been bedevilled by hamstring headaches, the most recent arising on Saturday.
There are lots of options. Philly McMahon is the only member of last year's All-Ireland 15 yet to feature this year, but he's back to fitness now and his credentials arguably grew in his absence against Tyrone.
Michael Fitzsimons is another proven man-marker; likewise Eoin Murchan (currently out, injured hamstring) but he is designed for tracking buzzing danger men of equally diminutive stature.
Then there is the tantalising X-factor: might Rory O'Carroll be coaxed back after a three-year-plus absence?
In truth, nobody knows. It would appear a long shot. But the very existence of that question underlines the need for a formidable full-back presence to get Dublin's historic mission back on track.