Jose Mourinho isn't the kind of man to hold deep lying regrets. From 50-page analytical dossiers at the end of every season to grinding out 1-0 wins against even the most inferior of Premier League opposition, the whole essence of the Portuguese's philosophy is that nothing gets left to chance.

Accordingly, there's no room for regret; you're either good enough, or you aren't, but errors spawned from miscalculation and underestimation are simply unacceptable. That's why Petr Cech and Didier Drogba were replaced by Asmir Begovic and Radamel Falcao this summer. That's why Chelsea spent £23million on winger Juan Cuadradro in January, despite Eden Hazard and Willian's places in the starting Xi coming with virtual guarantee.

That's why Kevin De Bruyne, the subject of this article, managed just three games under Mourinho before being sold to Wolfsburg in January 2014; because at the time, as a youngster struggling to overcome the immense competition in Chelsea's squad, retaining him in hope of eventual bloom was too much of a risk.

No doubt, the Chelsea boss appreciates the Belgium international's talent, else he wouldn't have been selected for Mourinho's first competitive fixture upon returning to west London at the beginning of the 2013/14 campaign.

But in a team the Portuguese only truly found the right balance for twelve months later, through the additions of Nemanja Matic, (which De Bruyne's departure essentially funded) Diego Costa and Cesc Fabregas, the lackadaisical start to 24 year-old's Blues career was an unavoidable issue. And as we know from the parallel fates of Andre Schurrle and Mohamed Salah, once Mourinho's decided you aren't right for his mentality, you don't have long left as a Chelsea player.

Considering how De Bruyne has flourished over the last 18 months, however, the Blues boss might have been a little more patient. Since leaving Chelsea he's produced amongst the most formidable output in European football; ten goals and 21 assists (a Bundesliga record) as the beating heart of a rapidly improving Wolfsburg side who finished second last season. Not a single Chelsea player, not even PFA Player of the Year winner Eden Hazard or club top scorer Diego Costa, contributed to as many league goals as De Bruyne last year, in spite of winning the title.

Mourinho can live with the attacking midfielder dominating another top flight, miles away where he can't hurt Chelsea. The real concern comes amid rumours that he's about to join Manchester City - the Blues' biggest title rivals - for £47million.

On top of that, De Bruyne seems like the perfect fit for the right side of the Citizens' formation, naturally drifting into central positions in the manner Manuel Pellegrini desires, and the club's more relaxed, less self-sacrificial mentality. Whilst Mourinho still feels he made the right choice in letting the Belgian go, he might be overwhelmed by juxtaposing emotions in a year's time, should De Bruyne prove to be the missing piece in Pellegrini's jigsaw.

That being said, the art of Chelsea's global spanning loan army, which De Bruyne was a part of for three quarters of his Blues career, is that the club can afford a few wide calls in the transfer market. They made a £7million profit on the midfielder in the space of two years and just nine competitive appearances; whilst that may not be enough to compensate for City claiming the title with De Bruyne pulling all the strings, another Chelsea youngster of equally prodigious ability is never too far away. There's already plenty of hype surrounding Bertrand Traore, Isaiah Brown and Patrick Bamford, for example.

Likewise, at its highest level, football is a war of ideas and interpretation. One manager's deadwood is another's star player; one's defensive sturdiness is another's pessimism; one's free-flowing attacking football is another's dangerous idealism. So regardless of whether De Bruyne becomes a Premier League winner at Manchester City or even a future proprietor of the prestigious Ballon d'Or, Mourinho will always believe he made the right choice in selling a player who, according to the Portuguese, couldn't handle the competitiveness of Chelsea's squad and was only ever interested in being treated like a star.

The history books, however, might go on to view the situation a little differently - and label De Bruyne's departure as one of the few bad calls throughout Mourinho's otherwise impeccable career.