The ire isn't so much related to the "loss" of Lukaku to a rival club but more so driven by the sense that once again Chelsea's board are perceived as negligent in their duty to secure the right deal for the club when selling players.

In 2014, Mourinho's impatience with Lukaku's desire for first-team football at the Bridge saw the Portuguese encourage the striker's sale to Everton for £28 million. He also advised Chelsea not to bother inserting a buy-back clause in the sale contract as he didn't believe the player would ever reach the level he required to merit the reduction in the up-front fee received when such terms are agreed.

Were Chelsea a club that advocate longevity when it comes to the tenure of their managers, let's say in an Arsenal way, then it might be understandable that they paid heed to Mourinho's "advice" regarding Lukaku. But this isn't the general scheme of things at the Bridge, where owner Roman Abramovich's impatience at perceived failure regularly manifests itself in the form of hasty managerial departures.

Last summer, Chelsea attempted and failed to pry Lukaku away from Goodison Park, as a bid of £57m was deemed insufficient to persuade the Toffees to sell. Twelve months later, £75 million was the price Man United paid to secure his services and despite the London club matching the offer, the deal went the way of United.

While some Blues fans are currently kidding themselves that Lukaku isn't as good as he thinks he is and suspect that Mourinho only persuaded the United board to sign him to get back at Chelsea, the club that sacked him less than two years ago, there are plenty that believe the striker, now 24 years old, is the finished article.

Lukaku's current Premier League stats, 186 appearances, 85 goals, 34 assists speak for themselves, and, if the stories are to be believed, Antonio Conte is as peeved with the Chelsea board as the supporters who revere him for not securing his services or having a contract in place that would have facilitated this.

Lukaku isn't the only example of Chelsea shooting themselves in the foot when selling young players. Playmaker Kevin De Bruyne, another player discarded cheaply by Mourinho, subsequently blossomed at Bundesliga outfit Wolfsburg who made a handsome profit on the £18 million paid for the player in Jan. 2014 when selling him to Manchester City for £55 million just 18 months later.

Then there is the case of defensive midfield dynamo Nemanja Matic, a £2.25 million makeweight in the deal that saw Chelsea sign David Luiz the first time around. £20 million was the cash adjustment paid to Benfica for Luiz in January 2011, Matic was clearly just an afterthought.

Three years later, the Serbia international, at the request of Mourinho, who else, was back at the Bridge -- but it cost Abramovich £21m to sign Matic as there was no cordial buy-back clause in his sale contract.

Of course, the penny has finally dropped in the Stamford Bridge boardroom that it might be prudent to insert buy-back clauses into the contracts of the myriad youngsters the club churns through as the recent sales contracts of Bertrand Traore to Lyon and Nathan Ake to Bournemouth testify.

As far as Lukaku is concerned though, it's a case of Chelsea shutting the stable door after the horse has bolted. With the striker now out of the transfer equation, Abramovich must dig deep into his wallet again to keep Conte happy and bring in a top-class forward to replace want-away Diego Costa.

Pierre-Emerick Aubameyang of Borussia Dortmund, Alvaro Morata of Real Madrid and Andrea Belotti of Torino are all in the frame for an expensive move to West London. Abramovich may have a bottomless pit of money when it comes to bankrolling Chelsea, but as the Lukaku to United move exemplifies, sometimes cash isn't enough.

At present, it remains a mystery exactly who will lead Chelsea's line against Burnley come Premier League kick-off day which is now just a month away. It's not good for Conte, it's not good for Blues supporters and it's not good for the club.

With hindsight things could have been a lot less problematic at the Bridge, the venue of the greatest soap opera in football. Under Abramovich though, triumph eventually smothers adversity and no doubt it will again this time around. Chelsea will march on and the current frustrations will be forgotten.