IN or around the 20th minute of Saturday's massacre in Tullamore, Ger Cunningham dropped Liam Rushe from Dublin's attack to centre-back and Shane Durkin to a sweeping role alongside.
From there until half-time - some 21 minutes later - Dublin conceded just three points.
Which, against the gusty gale howling directly into the Dublin players' faces, ranked as quite the defensive coup.
The other notable thing about that particular juncture in the game was that prior to Cunningham's tactical intervention, Dublin had already conceded 3-10.
Quite how a team can go from the precipice of victory - as Dublin did the previous Sunday as David Treacy stood over that late free that would have negated the need for this replay - to the murky depths of devastating, potentially season-ruining defeat - as they did on Saturday - takes some figuring out.
But the reasons were everywhere.
According to Cunningham afterwards, "we did it (brought back a sweeper) inside four or five minutes. We did it nearly straight away," though that wasn't particularly apparent.
Certainly, his full-back line were left criminally exposed in those gory first 20 minutes, in spite of what was going on in front of them.
Doubtless, Cathal Mannion is an assassin inside forward, as his first two, precisely dispatched goals, demonstrated.
But Dublin walked around with a big red target on their temples too.
Cunningham's reasoning for the fatal drift of his half-back line to a part of the O'Connor Park pitch so as to make them redundant bystanders to Colm Callanan's long pucks and those measured and inventive clearances from the Galway full-back line was that had they not gone with their men, Galway might have done damage from further out.
Though surely, not nearly on the same scale. And there were plenty of flashing high-vis hazard signs from the drawn game in Croke Park.
"He varied it very well," he said. "It wasn't his tactic to go long all the time."
But Callanan did, more often than not, go long.
And oftentimes, it was terminal to Dublin.
In Cunningham's defence, Mannion's third goal came from a long Callanan puck out that bounced just 14 metres out from Alan Nolan's goal, behind Dublin's full-back line.
Regardless of defensive formation or constitution, that amounted to nothing more complex than a basic error, though Dublin were very clearly frazzled at that stage.
And even in the drawn game, Callanan landed puck outs into space behind Dublin's half-backs whereas Alan Nolan was offered no such expansive landing zone in ether match.
Truly, it's hard to think of a player being so sorrowfully missed as Peter Kelly on Saturday evening.
There were factors, of course.
Eight points down and seeing stars, David Treacy was fouled by Johnny Coen and Dublin had a penalty.
Treacy's went for the top right hand corner of Callanan's next and missed.
"At that stage you're looking for something to settle you and we needed it," reflected Cunningha,
Neither that, nor Paul Ryan's miss in injury time, would have amounted to anything more than window dressing.
Because everything comes back to that opening passage.
In total, Galway's full-forward line of Mannion, Joe Canning and Jason Flynn shot 5-15.
Collectively, the other 16 player used on the day by Anthony Cunningham scored 0-4.
Ger Cunningham now, has a huge job to build something from the rubble of this devastation.
The only microscopic consolation for Dublin now is that they've been down this dark road before.
leinster shc replay: dublin 0-0 galway 0-0