Some Chelsea fans are so blinded by nostalgia that they refuse to see reality.

When Jose Mourinho arrived at Chelsea in 2004, they were entering their 50th season without a league title, and just participating in the Champions League brought about the kind of excitement it would bring Tottenham fans today. Therefore it is perfectly understandable that the fans are standing behind the man they perceive to have built the modern Chelsea identity.

It is the same nostalgia with which Newcastle and Liverpool fans greeted the returns of Kevin Keegan and Kenny Dalglish respectively for ill-fated second spells. While Mourinho is a better manager than ‘Kings Kev and Kenny’ put together, the principle is the same.

To the modern generation of fans, Mourinho simply is Mr Chelsea. Even his biggest detractors would admit his ‘us against the world’ approach has proved perfect for a 21st century Chelsea so disliked for the wealth of its billionaire owner.

Behind the brash façade however, lies the reality that no other manager would be able to keep his job after guiding Chelsea to three league wins in three months. And even taking this season out of the equation, the Chelsea of Mourinho’s second spell have never got anywhere near the greatness of his first Chelsea team, or that of his Porto or Inter sides.

Yes it was impressive the way Chelsea strolled to the title last season, but they were faced with probably the weakest Premier League since the competition was created in 1992; a Premier League which saw all of its participating teams comprehensively dumped out of the Champions League by the second round.

Where Mourinho’s first Chelsea team was one of the best in Europe, his team of last season was simply a big fish in a small pond. A warning sign of his team’s soft underbelly came when they were knocked out of the Champions League after being outclassed by a PSG side which spent a full 90 minutes with ten men.

Those Chelsea fans who ask ‘who could possibly replace Mourinho?’ should show more faith in the decisions of owner Roman Abramovich. Derided in the media for sacking managers left, right and centre, Abramovich’s trigger-happy approach has actually been surprising in its success. A particular standout was Carlo Ancelotti’s side which won the double with a fantastic brand of attacking football.

The most surprising part of Abramovich’s reign however (and the most worrying for Mourinho), has been the success of Chelsea sides which have changed manager in the middle of a season. In 2007, Mourinho was replaced by the unheard of Avram Grant. Yet despite universal disbelief at the move, Grant was able to do what Mourinho never could and defeat Liverpool in a Champions League semi-final, before falling within a John Terry slip of the trophy against Manchester United.

Next up in the caretaker role was Guus Hiddink, who restored much-needed stability after Luis Felipe Scolari was sacked. He was able to bring the FA Cup to Stamford Bridge and was controversially beaten in the last minute of the Champions League semi-final by a Barcelona side considered by many to be the greatest ever to play the game.

After Andre Villas Boas was unable to inspire the 2012 team, club legend Roberto Di Matteo stepped in. Of all the managers Abramovich had hired, Di Matteo seemed least likely to bring any success, with his only top flight experience coming as manager of West Brom, where he was sacked. Yet against all odds and unlike all his predecessors, Di Matteo managed to deliver the Champions League.

Six months later it was Di Matteo’s turn to be controversially replaced by one of Mourinho’s biggest adversaries, Rafa Benitez. Hated by the fans, Benitez still enjoyed success at Chelsea as he rode over a cacophony of boos to lead the club to the Europa League title and comfortable Champions League qualification, something Mourinho is starting to look like he may not deliver.

For the owner of a club like Chelsea, the be all and end all is to qualify for the Champions League. This is why despite regular calls for his head, Arsene Wenger has been able to keep the Arsenal job for nearly 20 years. Had he once finished outside of the top four, it would have been a financial disaster for the club and Wenger would almost certainly have been sacked.

If it gets to the point where Abramovich feels Mourinho cannot ensure Champions League qualification and the financial windfall that comes with it, he is well within his rights to look elsewhere, regardless of what the fans think. And history shows there are worse things for Chelsea than a mid-season change in manager.