Bakayoko, Dembele, Gabigol and the worst 15 transfers of the season so far

Chelsea spent as much on the French midfielder as they brought in from the sale of Nemanja Matic to Manchester United, but they can consider themselves to be down overall on that particular £40 million transfer front. While one proven performer headed for the exits, the man drafted in from Monaco as a natural successor has struggled to get to grips with life in the Premier League.

Winner of the prestigious Golden Boy award in 2016 after helping Portugal to European Championship glory, the 20-year-old midfielder has suffered a rather humbling fall from grace. A high-profile move to Bayern Munich failed to deliver the expected results, while a forgettable loan stint at Swansea has further dulled a once glittering reputation and rocked seemingly fragile confidence.

The Iceland international has, like those around him at Everton, improved over recent weeks, but there is still much work to be done if he is to justify a hefty price tag. The Toffees paid Swansea £40 million for the 28-year-old playmaker but have just four goals and one managerial change to show for that investment, with a summer of big-spending having delivered little reward.

Once identified as the man to fill the boots of Neymar at Barcelona, the France international set about forcing through a switch to Camp Nou. A 20-year-old with just two seasons of senior football under his belt was considered to be worth €105 million, but an untimely injury after just 51 minutes of La Liga action means the youngster still has everything to prove if he is to avoid becoming one of the most expensive flops of all time.

A man who only made his senior debut in August 2016 offered enough during a loan spell at Alaves to convince Real Madrid that it was worth raiding the ranks of cross-city rivals Atletico. Their French recruit has, however, been handed just three La Liga starts and two in the Copa del Rey to remain on the fringes of the fold. At 20 years of age, though, he can still be considered one for the future.

The 23-year-old forward has been here before and must feel as though he is stuck in his own Catalan version of Groundhog Day. Not quite good enough to star for Barcelona but boasting enough ability to impress elsewhere, those at Camp Nou seemingly cannot make up their mind on the Spain international. Just a few months after activating a €12 million buy-back clause, a lack of game time means the inevitable exit talk has started to circulate.

Four goals in his opening 10 appearances for Wolfsburg bode well for the Belgian after making a loan switch from Liverpool. He has, however, now gone seven games without finding the target to look more like the frontman never truly trusted by Jurgen Klopp at Anfield. The 22-year-old is fast approaching what could be a pivotal career crossroads.

The Turkey international has few excuses for having made a shaky start to his time with Borussia Dortmund. With over 200 Bundesliga appearances to his name from spells at Freiburg and Bayer Leverkusen, the 28-year-old should have been a safe choice to slot in at centre-half but has seen his positioning and reading of the game regularly called into question.

Was a man in demand over the summer as the exit door swung open at Hoffenheim. Borussia Dortmund eventually won the race for his signature, with competition from the likes of Tottenham fended off to seal a £4.5 million deal. The 23-year-old full-back has looked lost at times, though, on the grandest of stages, with his unfortunate faults being particularly highlighted in a disappointing Champions League campaign.

Another move, another disaster for a man once considered to be one of the hottest prospects on the planet. Having failed to make an impact at Inter – with no return offered as yet on a €29.5 million investment – the Brazilian forward has now lost his way in Portugal while on loan at Benfica, with just one appearance made in the Primeira Liga as his struggles for form and game time continue.

Being allowed to snap up a World Cup winner with 350 senior club appearances to his name should have been considered quite a coup for Juventus, but the Serie A champions have barely seen their summer acquisition. The 29-year-old defender had to wait until November before making his debut, and he then lasted just 68 minutes before being forced back onto the treatment table to spark talk of his loan from Schalke being cut short in January. 

AC Milan rolled the proverbial dice over the summer and, following such sizeable investment, any number of their ill-fated additions could have made this list. Leonardo Bonucci and Lucas Biglia are among those to have flattered to deceive in a hugely disappointing campaign for the Rossoneri, but it is a Turkish forward who cost over €20 million who has arguably been the biggest flop, given the undoubted ability he possesses.

Having finally shaken his reputation as a home bird with Benfica, Marseille decided to roll the dice again when acquiring the Greek striker for €15 million. Unfortunately, the 29-year-old has looked more like his former self from Fulham than that which thrived over the course of two spells at Olympiakos, with just two goals netted in Ligue 1 so far.

A Champions League winner with 133 caps to his name who has graced the books at Ajax, Real Madrid, Inter and Galatasaray – what could possibly go wrong? Nice have found out the hard way that the answer to that question can be ‘plenty’, with Sneijder having proved to be one experiment on a fading force too far following the rejuvenation of Mario Balotelli. The Dutchman has made five Ligue 1 appearances in five months.

Arsenal may have once seen enough in the Frenchman to persuade them that he was worth the risk, but the languid frontman is now 24 years of age and showing little sign of fulfilling his potential. He left the Gunners with one goal to his name, and five in total across four loan-laden years, and he is yet to open his Ligue 1 account for Toulouse as the decision to hand him a three-year contract – even as a free agent – starts to be called into question.