The inside story of why things went wrong for Kevin De Bruyne at Chelsea

Had the 67th-minute strike at Stamford Bridge on Saturday been the only shining moment, Chelsea could have cussed their luck in losing to Manchester City. But they were comprehensively undone by Pep Guardiola's side, and the single-goal deficit belied a besting as great as Blues have copped in the last year.

There were excuses, many of them legit: the lack of recovery time from Madrid; the harder week; the smaller squad and longer travel schedule. But perhaps the biggest imbalance in the sides was down to something far more tangible: Kevin De Bruyne.

The Belgian could have been Chelsea's superstar, the story goes – though that is probably only a part truth.

“I don't know honestly, what happened in the past,” said Conte, when asked about the 26-year-old. “But for sure we are talking about a top player, the complete player. He’s good – technical, fast, and he works hard for his team. He is the complete player.”

That complete player was, of course, Chelsea's from 2012 to 2014. Spotted by the club's scouting network before his October 2011 visit to Stamford Bridge with Genk in a Champions League match, he was a Michael Emenalo acquisition, rather than one brought in by any Chelsea manager.

The then 20-year-old showed little in the 5-0 humbling by Blues: looking sluggish, and only adding a couple of perceptive balls to the match. Most there on the night wondered what all the fuss was about.

One of those was Andre Villas-Boas, who on the player's signing for £7m in January 2012, felt moved to tell us: “He is a player the club have scouted for some time and I am a manager who respects club policy.”

The upshot was that De Bruyne would stay with Genk for the remainder of the season. After an uninspiring summer, he was packed-off to Werder Bremen on a season-long loan. It was a move which would be his making, with regular loan reports remarking on his impact in what was, albeit, a relegation-threatened club, in a much poorer league. But what also came back was the mood music that De Bruyne expected more: a matter which would dominate the rest of his time on Chelsea's books.

When he returned to his parent club in the summer of 2013 it was not at the behest of the manager - by then Jose Mourinho - but again Emenalo's doing.

The Nigerian's judgement on long-term prospects has been hit and miss: but when he has got it right, he has tended to get it very right. But Mourinho's methods required more than just potential, and there were reports of friction between the two from early on.

De Bruyne, training camp sources said, believed he was worth more than the lower-order squad place he was afforded. Mourinho, similar sources attested, believed the player had an over-inflated belief in his own importance.

All of this came to a head in the unlikely setting of Swindon Town's County Ground in a League Cup game on September 24, 2013, where De Bruyne put in a dreadful, half-hearted performance, leading some to question whether he was even trying. He was hooked off with 12 minutes to go, and Mourinho was fuming.

That was it for De Bruyne at Chelsea: he immediately had his Cobham car-parking privileges re-aligned to that of the Under 21s lot, and his file was unceremoniously dumped in the out tray. When he left for Wolfsburg in January, it was good business for all: £18m for a man who didn't want to be here.

Manchester City, of course, offered the twist in the tale in the summer of 2015. With major investment in his talent, De Bruyne was made a player who was too big to be allowed to fail. While some appear star struck in the headlights of a mega-deal, the £55m valuation (of which Chelsea received a handsome portion) seemed to add weight to his personal belief.

Why couldn't Chelsea extract all of that potential, then? Well they could have.

The berth of Frank Lampard, the man to whom De Bruyne is most often likened, became empty at Chelsea less than six months after his departure. And Mourinho was fired less than 18months after that – a long time in football, but others have endured longer on loan.

There were undoubtedly mistakes on both sides, but it seems unlikely De Bruyne will rue that. And, with a new midfield based around Tiemoue Bakayoko, Chelsea perhaps only think of it fleetingly.

City have a great player in De Bruyne, but in terms of ability, pace and temperament, he is barely recognisable as the one that turned up at Chelsea almost six years ago.