A new era for Irish football begins in the strangest of circumstances. When Stephen Kenny was promised the keys to the top job, he was preparing to assume control in two scenarios.
The Dubliner would either be taking over after a failed Euro 2020 qualifying campaign or in the aftermath of a major tournament summer.
Nobody envisaged this bizarre halfway house handover. It's far from ideal, especially when McCarthy was well-liked by players, but the FAI's desire to move quickly does at least give all of the parties the opportunity to get their head around it.
Footballers are used to managers coming and going. Difficulty for some can represent opportunity for others. The show will go on. If Kenny starts off on the right foot, the squad will concentrate on the present tense.
The 48-year-old is a glass-half-full thinker and was not fazed by the idea of Slovakia being his first match, although it would appear he will have more time than that to prepare.
Friends say he knows this is an opportunity of a lifetime and it will be fascinating to see how he adapts to it.
His background naturally results in comparisons with Brian Kerr, although Kenny is not overly keen on that line of thinking.
Granted, neither were players of renown and they were immersed in coaching by their early twenties, while earning a living in the real world. In that context, the rise to the biggest management role in the country - without any link to English football - is extraordinary.
But it's simplistic to conclude that Kenny is Kerr Mark II, much as it's inevitable that the point will be made.
He is his own man and it was the personality of his club sides and his ability to alter Irish stereotypes with their approach to European games that advertised his claims for elevation whereas Kerr's extraordinary feats at underage level secured him the ticket.
Descriptions of Kenny as a novice overlook that he's taken charge of 46 games in Europe, including against higher-level opposition than your average international opponent.
The tactical aspect of the brief won't be new. His big challenge will be the scrutiny and the profile. That is the step into the unknown.
In the past, Kenny made mistakes by going into dressing-rooms where he had inherited staff or players he didn't want. That's why his freedom to bring in Keith Andrews and Damien Duff as assistants is significant.
He favours a small coaching staff over a large team. Duff's "work ethic" was cited in a brief FAI TV interview yesterday, and he will essentially slot into what was Jim Crawford's post with the U21 side.
Duff's standing in the game will help with players, of course, but Kenny wanted coaches with recent high-level experience and an awareness of any evolving trends. Being in touch with the modern game was higher up the list of priorities than seeking a seasoned coach that might be out of the loop.
Duff and Andrews are both viewed as forthright, and will have an active role on the training ground, and in one-on-one engagement with players.
Alan Kelly was retained as goalkeeping coach with his analytical approach respected and there's a buzz around a new crop of 'keepers in the younger age bracket.
For all that Kenny has a strong philosophy on how his sides should play, he is very much a manager that allows the coaches to do their thing in their area of expertise.
His ambition and determination is often underestimated because of a softly spoken public persona, the silences that are wrongly construed as hesitancy when he is often just choosing the words carefully.
Those who have worked with him closely know that he's far from a soft touch. As a former player once put it: "He's a great man, but he would run you over to get to the other side of the road".
Remember, the FAI and John Delaney initially thought that the Dundalk manager would be content to accept the U21 job. He stood his ground, and didn't take a backward step.
There will be conviction in his personnel choices. Defenders who step out and pick a pass will be vital, so John Egan may be safer than Shane Duffy although Kenny has always sought athleticism and physicality from his sides. Pragmatism will be employed too.
The strong-running Norwich attacker Adam Idah is well placed to thrive as a No 9 under Kenny. He's more likely to lead the line than the diminutive Aaron Connolly, who was used on the left wing at U21 level. Positive wingers will come to the fore in his favoured 4-3-3 shape. Callum Robinson and Callum O'Dowda will be in the mix, and Robbie Brady should come back into the fold.
Box-to-box midfielder Jayson Molumby is ready for extra responsibility now, and a permanent promotion for Troy Parrott is on the cards too, although his specific role is up for debate. He was shunted around a bit with the U21s.
Funnily enough, the one disappointment that Kenny suffered in that role, a 1-0 loss away to Iceland in front of less than 100 people, came when the opposition sat behind the ball and soaked up pressure.
In other words, they adopted a strategy familiar to the Irish senior side for a good part of the last decade. This was a role reversal for a team wearing green, a reflection of how Iceland had viewed them through their homework.
There is no doubt that Kenny has been fortunate to inherit a good crop of players, and declaring this generation his work would do a disservice to the coaches who have had a longer-term role in their development.
change in mindset
Jim Crawford, Tom Mohan, Colin O'Brien and others have all contributed to the change in mindset that was necessary; a drive towards Irish sides with a defined pattern of play.
What Kenny has done in a short space of time is construct an U21 team that showcases the best of what is coming through, and the hope now is that the senior team will sit at the top of the production line as opposed to operating as an island in itself. The stakes are higher, but the identity should be the same.
His work behind the scenes will make or break him, but this won't be a manager who publicly complains about the players at his disposal for the sake of self-preservation.
New FAI decision-makers have bought into that vision as an idea they would like to work with, an outlook that could change the image of the team and that future starts now. Whatever happens, you can rest assured it won't be more of the same.