In all the great unveilings of Irish managers over the years, it has been possible to note retrospectively that the reasons for their eventual downfall were identified on these opening days, on the moment of their triumphant arrival itself.
For Brian Kerr, it was the sense he would have to distance himself from the triumphant and expectant hordes who had gathered in the Great Room of the Shelbourne Hotel to celebrate the appointment of one of their own; for Steve Staunton, it was the insistent 'I'm the gaffer' and the sense of doom these words would eventually convey; for Giovanni Trapattoni, it was his halting English and his emphasis on the result which with time would come to be an emphasis on dysfunctional functional football.
Yesterday it was possible to believe that anything was achievable, that there were no longer any boundaries to the march of the nation. The FAI have appointed perhaps the only man who would be able to handle somebody as unpredictable as Keane. O'Neill was wry and self-deprecating and made no attempt to talk down Keane's reputation. In fact, he talked it up. He hid from nothing, stating that he felt Keane was wrong in Saipan and joking that if a manager of Alex Ferguson's stature – "one of the greatest managers of all time" – had chosen to "get rid of him, that will always be in the back of my mind."
He had to explain that this was a joke, something that was necessary on a few occasions as the audience got used to his humour and he dealt with all the issues that needed to be addressed. For most of the day, Keane was the issue being addressed.
Keane was watching Aston Villa play Cardiff but he dominated the day's events. It is a cliche to say that a scriptwriter couldn't make up some true life event, but no scriptwriter would have allowed the removal of conflict and jeopardy which was brought about by Keane's absence.
Yet it didn't matter. All human life presented themselves at the Gibson Hotel yesterday. "Where's the bar?" one man said as he arrived at the accreditation desk, a reminder that these events can accommodate adrenaline junkies too. In fact, they might have been designed for them.
The media, the sponsors, the football people of Dublin had all showed up to witness this great triumph.
O'Neill's arrival in one area of the hotel led to some herding of journalists into a separate room as if he was one of Nigel Tufnell's precious guitars and we couldn't even look at him.
Ten minutes before one o'clock, the panelled walls alongside the press conference room slid back to reveal the football family. They looked like a group of eminent psychologists or advertising folk engaged in a controlled study of a curious breed, in this case journalists.
The FAI board members, chief executive John Delaney and assorted sponsors were suddenly among us and even more suddenly O'Neill was too, shaking hands with men in suits, men in hats and men in Ireland jerseys.
O'Neill was introduced to the crowd and sat at a table decorated with a banner advertising the friendly game next week against Latvia as if O'Neill was here to promote a prizefight rather than begin a two-year contract. O'Neill engaged in a characteristically articulate explanation of what he hoped to achieve. Of course, there are those who are anticipating a prizefight.
O'Neill on his own would have been an exciting appointment and when he moved away from Keane and talked about what he would do with the team, it was possible to understand why.
He would watch matches in Ireland, he explained, hoping that he could uncover a player who had been missed by English clubs. Given that Trapattoni had to be persuaded to watch games in England, where the international players play, this was a significant improvement.
He had talked to some of the youth coaches yesterday morning, who told him there were a number of players under 16 who had potential. That, he joked again, was "a fat lot of good to me".
O'Neill has a two-year contract, which will run for as long as Ireland are involved in the European Championships, so he will emphasise results and, in doing so, will try to increase the talent he has to pick from.
Players from Northern Ireland would not be pursued, they will have to want to play for Ireland. "It will be very much down to one's own personal designs really. I will not be actively poaching anyone."
He would explore the ancestry rule as well. "Jack Charlton went back to someone sharing a drink with someone, you know, and it didn't do him any harm at all. Again, he's a big, big figure, did a fantastic job. It didn't worry Jack. To a certain extent, I was just having a bit of a joke there. I will have a look at it to see. You wouldn't really want to be picking someone who was just tenuous but I think the rules now are more clear than perhaps they were under Jack's time. It's something I would certainly look at."
These were the ideas for the future but yesterday he could only promise "ferocious enthusiasm" and he looked like a man who had good reason to feel, as he had stated in an interview yesterday morning, that he had been badly treated by Sunderland.
He made his feelings on Paolo Di Canio clear. "The owner chose otherwise and then appointed a manager for about 11 games who just about criticised everything that went on beforehand and is not actually in work at the moment."
His only reservation before he accepted the Ireland job was that he would miss club management but he had no hesitation about taking the Ireland job as he gave glimpses of that ferocious enthusiasm. There are no clauses in his contract which would allow him to leave if a Premier League club approached, he said.
Yet it will be Keane and his relationship with him that will hold the initial fascination. Keane will meet the media on Wednesday. Traditionally, the Irish assistant manager has talked to the press by the side of the pitch in Malahide. Sometimes, if it is cold, they will retire to the caretaker's shed. Keane will meet the media in a fine hotel and it is possible there will be even more interest in his press conference than there was in O'Neill's.
O'Neill seemed enthused by the prospect. He said he didn't miss having an assistant at Sunderland but Keane was there to do what John Robertson did, with an added bit of volatility.
"I really don't want him to change. I would imagine somewhere along the way . . . John Robertson who you would say is less volatile than Roy – who isn't? – and I would have had the occasional disagreement about either team selection or methods of things. But I knew he was right with me and I expect that from Roy."
His humour may be the best way of dealing with those moments when Keane thinks the world has become intolerable. In Saipan, Keane felt that way and O'Neill said he felt his new assistant should have acted differently.
"If you're going back to Saipan, way back in that time, I would have to say that my own view at that time is that I would have disagreed with Roy. I would have disagreed with him. I would have felt that, having qualified for the World Cup, it doesn't come around too often – for some great players it has never come at all – and here was this opportunity. He was the captain of the side, I can go back to my experiences in 1982 with Northern Ireland. I'm not so sure there was a great, general belief about the organisers that we might make it to the second stages so when we did do, we were kind of left a bit high and dry from the viewpoint of 'Where do we go now?' It wouldn't take too much for players to moan. We felt we were really big time now because we'd qualified for the quarter-finals but there was a hotel somewhere along the way in Madrid that we went in to. Did it affect us? Not really because you're there for the World Cup and it was fantastic."
O'Neill said he had raised this with Keane. "I think I mentioned that to him and then of course he retorted by saying he disagreed with my team selection in the 2003 UEFA Cup final. Unbelievable, unbelievable. He said he would probably have won it. So, yeah, we're going to have the occasional debacle."
These are two men who worked for Brian Clough, at times perhaps were two men who felt bewildered by Brian Clough and they are now bringing their own methods to the Ireland team. "Clough would have had some palpitations and I think he would have worried for both of us," O'Neill said.
O'Neill has never had any problems being his own man. "I would like to develop a style of play that we could identify with and not lose the inherent passion." On this point, he was twice asked if there had been a loss of enthusiasm among the public for the Irish team. O'Neill and Keane have, by the simple act of arriving, brought back the sense of passion. "John has kindly mentioned to me that there is big excitement around the place," he remarked.
The excitement will build this week. Keane's role will be dissected as the manager and assistant learn how to work together.
"Listen, I don't pretend to know him that fantastically well. I know him well enough. I've got to know him through the time we've spent on trips away for the Champions League games before I went up to Sunderland. As I said, I found him very engaging. Obviously, and the thing I like about him, is that he's very intense and he wants to do well. He loves football, genuinely loves football."
O'Neill said there was a misunderstanding over a reported comment that he would have taken Keane wherever he had gone in management but, in explaining the remark, he just advanced his admiration for him.
"What I said in the past, was if I was ever in the position to buy a football club, I would have immediately installed Roy as the manager, given him his budget, not speak to him for about six or seven months, which wouldn't be difficult, and let him get on with it. Maybe it was picked up from there. But in essence, if something has been lost in translation, there would be no reason for me, let's say it had been a club job, not to consider Roy."
Keane would be a manager again, he said, but this was an opportunity for him to learn. O'Neill offered a tantalising vision of Keane's role.
"First of all, we will confide in each other regarding what we consider the best team, I can see that sort of role. John Robertson played that role with me. John would have an input, eventually it would be my decision. I can see Roy getting involved with the players, that will be important. The younger players obviously will look up to him for a start. But that sort of thing can wear off.
"I actually believe Roy wants to integrate with the players and this is where I think on a one-to-one basis with the players he will be excellent, that is where initially I see this in the very short term. Obviously, when we get the two games out of the way we will have a wee bit of experience about ourselves and try to formulate a proper plan on the way through from there on."
O'Neill felt no need to assert his authority. "I don't want to make this an 'I'm the manager type thing'. I do not want to be running with that. But I'm the manager." This would be his job, Keane would be part of his team and both men would be giving everything they had. "I live or die by the results," he said. There may be more hysteria around this appointment but a manager's survival always depends on the same thing.