W hat is your favourite Diego Costa moment? Perhaps it is the one where he manages to get Gabriel Paulista sent off for a retaliatory kick just by standing quite near him, muttering and smiling like some horrible, handsome, impossibly terrible footballing Iago.

Or it may be the 2-2 draw with Tottenham where Mark Clattenburg books 12 players but not actually Costa, who has a hand in at least five of those yellows, all the while maintaining an attitude of prim and saintly innocence. Or the 3-1 defeat of Arsenal where Costa “scare-assists” his team’s final goal by running towards Petr Cech and making Arsenal’s goalkeeper perform his best impression of Shaggy from Scooby Doo confronted by a double-dealing fairground owner in a zombie mask.

Now we have this, the endless summer of Diego. As of this week Costa has spent half the summer and the opening week of the Premier League season holed up in his family home in Lagardo pretending to be inconsolably offended by a text message, all the while painting his current employers as bounders, cads, insufficiently “respectful” and so on. And in the process he has raised some profound issues about transfer fees and freedom of movement that have troubled even the biggest clubs for some time.

It is now 22 years since the Bosman decision in the European Court of Justice. Its effects are still working their way through football. What is certain is that the game has been transformed around it. And that clubs, governing bodies and players’ representatives all know we are not quite done with a process that might just have taken a step forward this summer.

But back to Diego. There was always a chance Costa’s time at Chelsea would end in a mess. Footballers are often described as being up for the fight. Costa is not just up for it. He is the fight, a man whose entire concept of sport is based on a no-holds barred test of all human capacities, including the mental resilience to rise above the goadings of a sharp-elbowed striker with an infuriating line in wounded innocence.

Costa has been a stellar Premier League player through two league titles, 57 goals and almost 400 fouls. It has been wonderful theatre at times. But at the end of this only the hardest heart could fail to raise a smirk of schadenfreude at the sight of Chelsea’s chief weapon of footballing chaos turning his guns on his own employer.

The situation is unlikely to have been eased by Costa’s comments in a fascinating interview in the Daily Mail. Relaxing on full pay at his family home, Costa suggested Chelsea are “treating him like a criminal”. Like Ariel, the harmless sprite of the forest, all he craves is to be “set free” – agents, contracts and sole approved destination pending.

Like a drunken row on a bus, it can take a while to understand exactly what everyone’s arguing about. A quick recap on how we got here. In January Costa was dropped briefly after some unrest behind the scenes and reports of a huge offer from China. Chelsea let it be known they had no intention of selling. Later that month Tianjin Quanjian said plans to sign Costa had been scuppered by new Chinese Super League rules. Costa suggested he had no intention of moving to China anyway.

Nobody really knows the exact ins and out of this mid-season shemozzle. All that is certain is Costa has been linked with a move away throughout his time at Chelsea; that his form dropped off a cliff after that; and that Antonio Conte sent Costa a text message in early June that apparently read: “Hi Diego, I hope you are well. Thanks for the season we spent together. Good luck for next year but you are not in my plan.”

Costa immediately leaked this to Spanish TV. His brother Jair announced that Costa was all set on moving on and had had “lots of offers”. Since when he has been at home in Lagardo, refusing to train at Chelsea, yawning off his club fines and now smiling, a little sadly, at his team’s understandable state of confusion at the start of the Premier League season.

The offending text message looks quite polite, all things considered. Certainly it’s more conciliatory than the text Costa might have received in similar circumstances from, say, Brian Clough or Stan Cullis. Footballing mores dictate that players simply don’t behave like this.

“In January, things happened with the coach,” he has said. “I was on the brink of renewing my contract and they put the brakes on it. I suspect the manager was behind it.” Well, yes Diego. This is how football works. You do not get to upset the coach mid-season and still have him warmly support your offer of a new contract.

From a purely footballing view he has no real gripe. Players are shifted on all the time and hear about it in far less courteous fashion. Costa has already been replaced, and replaced well, by Álvaro Morata. The path from here is well trodden. Get fit. Find a new club. And stop bleating on about respect.

At which point things get complicated. “Why won’t they let me go if they don’t want me?” Costa has asked. “I want to go to Atlético Madrid.”

The most obvious answer to which, not stated but implied, is that Chelsea are either refusing to sell, given the knockdown price Costa would fetch right now; or asking a price Atlético Madrid are unwilling to pay.

“I have rejected other offers,” Costa goes on. “They want to sell me to China or other teams. The language is better for me in Spain. If I’m off, I’m going to the club I want to go to, not the club that’s paying the most.”

At which point, if you listen closely, you can hear the entire superheated industry of professional club football starting to quiver. Costa’s lawyer has already suggested he will use “all legal mechanisms” to get the move he wants. How would this work in practice? In the real non-footballing world it seems laughable you could be denied the right to leave your job and work for another employer, or told only certain selected future employers are acceptable.

Football has come a long way since the retain and transfer system, whereby a player’s registration was owned by his club, who could in extremis refuse to release it and force a former employee into retirement. The Eastham judgment in 1963 relaxed this owner-and-chattel relationship. Bosman attacked clubs’ rights to have a say on a player’s employment beyond the end of his contract. Other rulings have already suggested there is headway to be made challenging further the power of clubs to “own” a player’s employment prospects.

Costa aside, this is a huge live issue given the number of top footballers currently out with a bad case of wanting to play for someone else. Philippe Coutinho wants to work for Barcelona. Virgil van Dijk wanted to work for Liverpool. Both have broken the code by taking steps to decide their own professional destiny.

Football will remain a special case. Clubs must be protected. Academies and player production systems must be presented with an incentive to produce footballers and stop the whole ramshackle circus from falling to pieces. But for all his infuriating sense of entitlement, his clod-hopping failed powerplay, Costa is undoubtedly on to something.

Three things are possible from here. Conte leaves before Costa does and the most improbable of Premier League comebacks becomes a very, very distant possibility. Chelsea and Atlético reach an agreement that makes this whole sorry mess disappear. Or, at a long shot, the man known during his Albacete days as “that fucking Brazilian” gets to wreak his own peculiar havoc on football’s transfer system at a time when, quite frankly, anything seems possible out there.