This upstart from Portugal with his smooth Euro-wardrobe, brooding good looks and gift for one-liners would never cut it in the toughest league in Europe.
After all he had never succeeded as a player, the league he had dominated with Porto was second tier and wasn't his 2004 Champions League triumph something of a fluke?
By taking Chelsea to their first title in 50 years Mourinho has proved those English sceptics emphatically wrong, though the "arrogant" epithet has stuck through a turbulent season marked by clashes with soccer officials, fellow managers and the media.
True, the 41-year-old had fine raw material to work with.
After a huge injection of cash from billionaire Russian owner Roman Abramovich, Claudio Ranieri had left his successor with a talented, improving side who finished second in the Premier League and reached the Champions League semi-finals.
Mourinho added strikers Didier Drogba and Mateja Kezman and brought with him Portuguese trio Ricardo Carvalho, Paulo Ferreira and Tiago.
Fleet-footed winger Arjen Robben and young Czech goalkeeper Petr Cech also arrived at Stamford Bridge for the new season.
It was the task of the "special one" to turn this band of big egos and individual skills into a fighting unit capable of breaking the Arsenal-Manchester United title stranglehold, a feat last managed by Blackburn Rovers 10 years ago.
TEAM ETHIC
For Mourinho the team ethic rules supreme. He had achieved outstanding success with much less talent at Porto and, with characteristic attention to detail, he set about teaching what he described as his "methodology" to players he considered technically skilled but tactically naive.
"Joe Cole is a good example," Mourinho said in a recent lecture on football management in Tel Aviv.
"He has learnt to play for the team rather than as an individual. The most important star is the team."
Midfielder Cole, who has excelled in the last few weeks, puts his improvement down to his boss who nagged him constantly from the pitchside and taught him to look up when the ball was at his feet and tackle back.
The Portuguese perfectionist said as late as February, with Chelsea already runaway league leaders,
Players describe Mourinho's training sessions, with the emphasis on tactics, as intense, concentrated and exhausting.
"It has been so different this year ... we are still working hard but it is more specific," Chelsea's Icelandic striker Eidur Gudjohnsen, signed by Gianluca Vialli in 2000, said.
Mourinho's highly organised and controlling nature may explain the run-ins he has had with footballing authority.
Sources close to him say some of his outspokeness, at least earlier in the season, was calculated to draw attention from his players so they could concentrate on their game.
ANGELIC MANAGER
Back in November he remarked: "Compared to many other managers I am an angel". Then he ran into trouble.
Criticism of a referee and describing Manchester United after a League cup semi-final as having cheated led to a fine.
In February he was out of the dugout at the Millennium Stadium in Cardiff and had to watch his side's 3-2 victory over Liverpool on television after making provocative gestures towards the crowd when Chelsea scored.
The fingers on the lips gesture earned him a reprimand.
More seriously UEFA fined him and banned him from the touchline for the Champions League quarter-finals, saying he had brought the game into disrepute in February when he accused Barcelona manager Frank Rijkaard and referee Anders Frisk of talking to each other at halftime during their Champions League game at the Nou Camp.
Swede Frisk later resigned saying he had received death threats after Mourinho's criticism.
Mourinho, upset at UEFA's reaction as well as British media coverage, has cut back on his public pronouncement since then, even pulling the plug on a Portuguese television talkshow after one edition.
He accepted he had to change his ways to fit into the ethos of English football and, with uncharacteristic deference, he refers to United's Ferguson as "the boss". The Scot, no stranger to controversy himself, has welcomed Mourinho's impact.
"He's brought something to the Premiership; he's got a humour about him," Ferguson said.
"We had a spat last year but...he's done great the lad. He's got a confidence about him that's suited well to his team."