Unquantifiable issue of spirit comes into the equation
They both hit the ground at full throttle early this summer and have more or less maintained their rampant form since.
The two best teams will meet in this afternoon's All-Ireland final and there is an impending sense that both will be travelling even faster when they collide today, like two runaway trains about to converge on the same railway line.
After the throw-in there will be debris. With fuel tanks fully loaded, and ignited by hair-trigger nerves, players will be hurtling towards man and ball at frightening speeds. Bodies will go down in those early stages; one hopes they will all get up again.
The common explanation for this manic state is that it's a case of survival of the fittest, players trying to survive what is actually an ordeal. One former player who was new to the big-game pressure of Croke Park described it in even more fundamental terms. His bewildered recollection of it was that, "You weren't trying to survive out there, you were trying to – you were trying to exist."
It must be agony for their parents and loved ones watching from the stands, or at home on television, if they can bear to watch it at all.
Most of the players involved today have been through this very public trial at least once before. A few on either side will probably buckle under the strain. But a big majority should be sufficiently battle-hardened to find their bearings, connect with their brains, and play the game ball by ball.
When the dust settled on that epic second semi-final three weeks ago, and Dublin were left standing with Mayo, the early consensus was that this one would be too close to call. They would both arrive on the fourth Sunday in September pretty much even favourites for the prize.
But as the game has loomed closer and the weeks have funnelled down into days, there's been a perceptible drift towards Dublin as the more likely champions-elect. Not a landslide by any means, more a tilt in their direction, a gathering intuition that they will prove to be the more complete squad.
Certainly more complete where it matters most: up front, where they seemingly have the better-stacked forward line. And it is a prodigious unit, physically imposing, strong in the air and full of running on the floor. This potent athletic capacity enables them to break tackles, engineer overlaps and create goal chances. On top of that foundation there is an impressive spectrum of skills. It is speckled with two-footed players who are comfortable passing and kicking off left and right; who can spin off a marker and score from tight angles; and who can shoot points from long range.
The Mayo forward line comes up short by comparison. If Cillian O'Connor and Andy Moran were, respectively, fully fit and in good form, the perceived gap between both attacks would diminish to almost nothing. But they're not, and it is here that the only clear daylight between the overall sides is located.
O'Connor has been Mayo's number one strike forward this year. If he cannot function freely then Mayo will struggle to accumulate a winning tally. If the reservations about he and Moran materialise, then it's Dublin's All-Ireland.
That's the pre-match reasoning and it is sound, as far as it goes. But of course issues that seem central in any prior speculation often become irrelevant as a game unfolds. Every game has its own organic energy; every game is subject to the chaos of action. There is no knowing what will happen at any given time today.
We do know however that both teams will keep playing regardless of the setbacks they sustain along the way. Both are mentally strong enough to absorb shocks and resume their incessant rhythm.
For both teams have that incessant quality about them. Dublin proved it beyond all doubt against Kerry in the semi-final. Mayo haven't had much need to prove it this summer but the Tyrone game showed it was there.
It is definitely there. The Connacht champions have the look of a team that is hell-bent on finding a way, one way or another. Their perennial problems in attack have been circumvented by that ebullient defence, epitomised by
Barrett and Keegan in the semi-final, and exemplified also by the likes of Vaughan, Higgins and Boyle. They have augmented their forward line with enormous effect. They have provided the platform from which Mayo's massive scoring rate has sprung.
Dublin will make it an absolute priority to keep these particular players at bay today. They will want to cut them off before they get out of their own half. And they have the industrial sort of running power needed to do it.
But the feeling here is that Mayo will still find a way. If O'Connor and Moran aren't firing, someone else will pick up the slack. If a few defenders are kept on the back foot, a few others will manage to escape. All over the field there is a powerful unity and conviction about their work.
Dublin right now look to have the superior firepower in attack. But if the unquantifiable issue of spirit comes into the equation, our guess is that Mayo will have the edge here. They are convinced that their time has come. They don't believe they deserve it; they do believe that they've earned it.
Mayo to find a way; Mayo to win.