He plays like a kid who has yet to feel the tickle of pressure roll down his spine.
Jack McCaffrey's game is a lyric at odds with the modern lust for systems. He runs as if the field is a playground bubbling with noise, no corner of it closed to possibility. If Jim Gavin's Dublin have begun to weave a spell of ungovernable, go-to-hell football this summer, their No 7 is becoming an emblem for that spirit.
Alan Quirke thinks of the quarter-final goal that beat Cork and, if anything, it was McCaffrey's composure that disarmed him.
Ordinarily a defender arriving into that precinct will resort to a kind of panicked trigger-pull, but McCaffrey simply adjusted his feet and nudged the ball. His gentleness was that of someone guiding a butterfly out through a narrow window slat.
The ball actually brushed Quirke's left shoulder as it passed him.
"It's amazing the fractions in the game," reflected the Cork goalkeeper this week. "Had it been another maybe inch or two lower, it probably would have bounced back out, but that slight contact just sent it up into the top corner.
"That said, it was a fairly cool finish for a young guy. Sometimes fellas might panic when they get into that range, but he side-footed it rather than blasting it. That was the big thing."
In a game threatening to be defined by Dublin's profligacy, McCaffrey's goal yanked it out of neutral. And the Hill, naturally, exulted, seeing in it the cavalier brilliance of a team rejecting the constraints of conventional thinking about how best to win a championship.
If Dublin represented a brazen philosophy, a distaste maybe for the faux intellectualisation of football favoured in some quarters, McCaffrey's smile was like a company stamp.
At 19, he has a city at his feet then, this swashbuckling kid who careers down Dublin's left flank like a getaway car. He has always been blindingly quick, as Tadhg Kennelly famously acknowledged at those AFL trials in the National Basketball Arena a year and a half ago.
Kennelly used the expression "freaky talent" when adjudicating on McCaffrey's 2.8 seconds time for a 20-metre sprint. It would, he said, have identified the kid as gold dust in Australia. But McCaffrey never caught that flight.
He'd grown up in a house where the sky blue jersey meant a good deal more than a summer fashion accessory. Noel McCaffrey was an All Star wing-back in '88, a fitness fanatic who once cycled to Tullamore to watch the Dubs in action.
He always had that independent streak that challenges formulaic expression and, by the time his son broke onto the north Dublin development squad as a 14-year-old, it was into Noel's care he went.
When that sheaf of development squad players then came together under a single Dublin banner at the age of 16, Dessie Farrell's was the voice they listened to. And Jack McCaffrey would subsequently play on Farrell's minor team, beaten in the 2011 All-Ireland final by Tipperary.
Pace was the first thing people noticed with young McCaffrey. Innate ease with a ball of any shape was usually the second.
In February '09, Jack scored a startling individual try for Belvedere College against Terenure in the Leinster Junior Cup, running from half-way before side-stepping the opposition full-back with an outrageous body-swerve.
For Farrell, the breadth of the kid's talent was matched only by an unusual maturity. Dessie recalls his first sighting thus: "I remember thinking to myself that he was a cut out of the oul' fella!" chuckles Farrell now.
"You'd know he was a McCaffrey for sure. I think Noel wouldn't disagree with me when I say that Jack is a much better footballer than Noel was, even though he won that All Star.
"But the first time I got speaking to Jack, he left me in no doubt that he was a great young fella too. With his general attitude, the respect he has for other people, just the way he carries himself. You can see the good upbringing in him, you can tell that he comes from a great family.
"Sometimes highly intelligent young lads can comes across a little nerdy or aloof, but he's just so well grounded. He's just a lad who's completely helpful to others, a deep thinker who's always willing to look at the bigger picture in terms of what's going on in other players' lives."
That intelligence has led him to follow his father's path of a career in medicine, a decision sure to challenge Jack's long-term sporting ambition.
Kennelly was desperately keen to get him back for another AFL trial last February, but McCaffrey declined politely. With his sprint test 12 months earlier, he would have qualified as fastest man in the 2011 draft.
Still, if he'd had wistful thoughts when watching his long-time friend Ciaran Kilkenny head to Melbourne for a trial with Hawthorn last October, McCaffrey kept them to himself.
The two had been friends and fearsome competitors on the north Dublin GAA scene from early teens, Kilkenny with Castleknock, McCaffrey with Clontarf.
They played together for Dublin U-13s alongside the likes of Paul Mannion and Emmet O Conghaile, all members of that beaten minor team two years ago.
If Farrell is pushed to choose a single moment on his watch that captured McCaffrey's quality, he nominates the kid's contribution to Gavin Ivory's sixth-minute goal in that All-Ireland final. The jet-heeled run was wonderful, but it was the timing of the off-load that made the score.
Dublin had practised that move on the training-ground, but it needed McCaffrey's brilliance to make it work.
They were, of course, left heart-broken by Colman Kennedy's sensational late goal for Tipp and, when Farrell and Dublin returned to win the 2012 final, McCaffrey, Kilkenny, Mannion and O Conghaile were all overage. They were also, by now, All-Ireland U-21 champions.
That victory was achieved under Jim Gavin's stewardship and is now regarded as the basis of Dublin's new philosophical blueprint.
Gavin believes in the marriage of youth and pace. He sends out his teams, above all, to go for the opposition's throat. One of his predecessors, 'Pillar' Caffrey, recently described the current team as having more pace than any Dublin team he'd seen since '74.
The ease with which McCaffrey especially has settled into senior inter-county has surprised Farrell. Indeed, it inclines him towards a cautionary warning.
For McCaffrey, Kilkenny and Mannion were all below their best when this year's U-21s suffered a surprise Leinster championship loss to Longford at Parnell Park. Young men can be susceptible to feelings of impregnability and, quite often, those feelings preface a fall.
As Farrell puts it: "That's the only thing you'd be fearful of, that things have gone so well so soon. Because, in football, you're only as good as your last game.
"Sometimes when you get into a bubble like that and are on the crest of a wave, you can never see the bad game coming. Then it jumps up and kicks you in the ass, particularly as the stakes get higher.
"That kind of pressure can be hard to deal with, so Jack is very much into uncharted waters now. It's not all plain sailing. But, if he can avoid injury, gain a couple more years of experience and not find juggling the football commitment with his medical studies too much of a strain, he could become one of the greats of the game."
McCaffrey's speed will, undoubtedly, have focused Kerry minds this week and there is speculation that Eamonn Fitzmaurice might be tempted to follow Meath's lead in the Leinster final and put their paciest attacker (Darran O'Sullivan) on the Clontarf flier's wing.
Meath manager Mick O'Dowd admits that he positioned sprint champion Eamonn Wallace on McCaffrey's side to create "a meeting of two equals in our eyes". The move was a qualified success, Wallace kicking two points from play, albeit McCaffrey being denied a Dublin goal only by the width of a post.
"They had a good battle," recalls O'Dowd. "Jack is a fabulous footballer, but maybe he was a little more conscious of Eamonn's pace than he might have been of others. It just made sense for us in that particular game that that was where Eamonn would start.
"But you work with what you have. If your full-forward is your fastest player and very effective in there, you're not going to drag him out to right half-forward."
In hindsight, Cork maybe had cause to rue not doing something similar three weeks later, for McCaffrey wreaked havoc down the right flank of their defence with a succession of slaloming runs, one of which might have drawn a second goal but for Quirke's smart near-post save,
The Cork goalkeeper, however, is not convinced that a pre-occupation with barricading one wing will solve tomorrow's puzzle for Kerry.
"To be fair, if you just concentrate on hitting McCaffrey's wing, the other wing-back – James McCarthy – has got massive pace as well," suggests Quirke. "Dublin probably have weapons to hurt you from both sides of the pitch.
"That said, McCaffrey seems to be a particularly explosive guy. There's been plenty of fellas over the years who've had pace to burn, but he can play as well. And it's the combination that makes him so good.
"I suppose he's like a younger version of Tomás ó Sé, probably quicker but not quite as big. For a guy so young, he certainly seems to be playing with a lot of freedom."
And that freedom is what defines McCaffrey and Dublin now. Hindsight, of course, might yet curse them as naive, but they are playing a game that's making a city tingle.
And restoring faith in childhood dreams.