THE breakdown of a relationship – for that is what it was – between Martin O'Neill and Sunderland owner Ellis Short centred around one key element.
O'Neill did not think the players he had inherited 16 months earlier were good enough to meet the expectations of the American who owns a football club in the north-east of England. The squad, he said, "lacked true, real quality."
Short thought it did not. In such a situation one man loses.
On Saturday night, in conversation over the telephone with Short, following a miserable defeat at the Stadium of Light, albeit against Manchester United, the champions-in-waiting, O'Neill found out a football certainty: you cannot take on a chairman with bad results.
It was after 9.0 when the call was made. O'Neill (61) has supported Sunderland for 49 years of his life. He had managed them for less than two. By the time the call was ended, so was his time in charge.
Key statistics did for him, the most damning being that Sunderland have won just four games at home this season and sit bottom of the Premier League form table.
They have picked up only three draws from their last eight league games. At home, they could not beat a Norwich side who played the majority of the match with 10 players following the dismissal of their goalkeeper.
Short's total investment in Sunderland is reckoned to be more than £100m.
Relegation this summer would be disastrous, with a new television deal expected to add a further £30m to the turnover of any club that plays in England's top division.
By the time Short phoned O'Neill on Saturday, Sunderland were one point off a relegation place.
Those close to Short felt he could not risk relegation as he waited for the spark O'Neill provided last season to rekindle.
O'Neill repeatedly called for time. This was his first full season at Sunderland, having taken over a team in the bottom three at the beginning of December in 2011. He spent £30m on Steven Fletcher, Adam Johnson, Danny Graham and Alfred N'Diaye. Only Fletcher has flourished.
Short felt he could risk losing Premier League status without a change and now, into a void that the Sunderland owner has tried to fill with O'Neill, Steve Bruce, Ricky Sbragia and Roy Keane, comes Paolo di Canio.
Di Canio's brief is simple enough. He has to get more out of the players, international players.
The contrast to the appointment of O'Neill – 27 years' worth of managerial experience and almost 900 games – to Di Canio – one club, less than 100 games – is stark. O'Neill was thoughtful and methodic, Di Canio emotional and impetuous.
"I believe I am at a stage now where I am a Premier League or Championship manager," he wrote after leaving Swindon Town in February.
"The right place for me is the place that has the ambition and the staff who want to bring in a winning mentality. The club needs to have set rules, which for me are discipline, desire, passion, work-ethic and a determination to get the right results to make everybody happy – namely the board, the fans and the club's players and staff."
That is more what the boardroom at Sunderland wanted to hear, despite its lofty ambition.
Such aspiration is a big enough ask for a conservative manager.
Di Canio's Swindon reign was littered with colour and controversy.
The club lost the sponsorship of the GMB Union on announcement of his appointment because of his stated fascist politics.
The Italian signed 15 players in that summer of 2011. There was a clash with one of them, Leon Clarke, in the tunnel after a game that was caught on camera. Clarke never played for Swindon again.
Di Canio substituted his own goalkeeper Wes Foderingham after 21 minutes during a defeat at Preston. Foderingham kicked a water bottle in tantrum as he left the field. The manager demanded an apology, which he got.
He took Swindon to the League Two championship and a Wembley cup final, which they lost.
On October 6 last year, Swindon had a transfer embargo placed upon them for breaking the limit on transfer fees and wages.
It was lifted on November 6 but the club's new chairman, William Patey, told Di Canio there would be no money for further spending.
The 44-year-old Di Canio responded by offering to pay £30,000 from his own pocket to keep Danny Hollands and Chris Martin, who had been at the club on loan. Under the threat of administration Swindon changed ownership.
Matt Ritchie was sold for £500,000 to Bournemouth, against the wishes of Di Canio, who resigned.
In the index of his autobiography, entitled 'Paolo di Canio: The Autobiography', come the following: argument with Atkinson, argument with Burns, argument with Capello, argument with Ferguson, argument with Trapattoni and argument with Wilson.
His second game in charge will be a Tyne-Wear derby at St James' Park, with both clubs fighting relegation.
In the corresponding fixture last season, the two sides were fined a total of £60,000 for a number of incidents, including both benches clashing.
Short has lit the blue touchpaper with his move for Di Canio. On what, no one is quite sure. (© Independent News Service)