There was a period not so long ago when Chelsea could have looked at Monaco’s midfield and congratulated themselves on their foresight, since Tiemoué Bakayoko was being kept out of the French club’s starting lineup by another youngster who was on Chelsea’s books and still is.

Mario Pasalic, a Germany-born Croatia international six months older than Bakayoko, has belonged to Chelsea since joining from Hajduk Split three years ago but has yet to contest a single game for them. Instead, like most of the speculative investments in Chelsea’s vast player portfolio, he has been rented out to others via a series of loan moves, including one the season before last to Monaco, where for the first several months of the campaign he was regularly chosen ahead of the player on whom Chelsea have just splurged a fee that could rise to £39.7m.

That is not to say Chelsea would have been better advised to put more trust in Pasalic, who may leave Stamford Bridge for good this summer. Rather the point is to underline that it is never easy to know how young players are going to develop. At 22 Pasalic is a handy player who did well again on loan at Milan last season and looks likely to have a fine career. Bakayoko, meanwhile, has become more than that, a deft monster who can stomp or glide through top‑class midfields and could be heading for superstar status. That evolution owes much to Bakayoko’s slightly tardy awakening and the influence of a former Chelsea midfielder, Claude Makelele.

Back when Pasalic was getting picked ahead of him, Bakayoko seemed to be at risk of being written off at Monaco. The club, who are among Europe’s shrewdest recruiters and developers, bought the player as a 19-year-old from Rennes for around £6m in 2014 but a year later the manager, Leonardo Jardim, had become exasperated by the midfielder’s failure to progress. That feeling began to form pretty fast after the player’s infamous debut in August 2014, when Jardim surprisingly selected Bakayoko to start against Lorient ahead of the club captain, Jérémy Toulalan, only to rescind the vote of confidence after 32 minutes and haul off the floundering, furious teenager.

It was more than two months before Bakayoko started another match and, thereafter, the rest of his season was marred by injury, inconsistency and a relationship between player and manager that Bakayoko admitted was “a little broken”. Bakayoko felt he was being treated unfairly while the manager believed the player was not helping himself, occasionally turning up late for meetings and not always training with full intensity.

Bakayoko, who was rejected by France’s prestigious Clairefontaine academy at 14 partially because a school report suggested he was hard work, but who recovered to make great strides at Rennes, was going through another awkward phase. That pattern continued into the next season, when Pasalic, rather than Bakayoko, tended to play in the position vacated by Geoffrey Kondogbia, sold to Internazionale.

Tiémoué Bakayoko, in action for Monaco against Juventus, can stomp or glide through top-class midfields. Photograph: Franck Fife/AFP/Getty Images

In January 2016 Monaco appointed Makelele as technical director and the former midfielder made nurturing Bakayoko one of his missions. That was the right influence at the right time because Bakayoko had realised he needed to focus more and had got in touch with one of his former mentors at Rennes, Yannick Menu, to ask for advice. If Menu was the gentle guide, Makelele was merciless. “He needs confidence but in order to be consistent in his performances he also sometimes needs to be straightened out, jolted,” Menu later explained. “He can slip into a comfort zone very quickly because Tiemoué is a peaceful person, not a rager.”

Bakayoko, encouraged by Menu and challenged by Makelele, resolved to get the best out of himself: no longer could his attitude in training be questioned and he enrolled in boxing classes and began to follow a strict diet. He added muscle to his tall frame and consistency to his game. He suffered fewer injuries, became cursedly difficult to shunt off the ball and loped with it dangerously from box to box. Quickly he became essential to Monaco. When he overwhelmed Marco Verratti and Thiago Motta in central midfield as Monaco beat Paris Saint-Germain early last season, it was a powerful indication of the campaign that was to come from player and team, a beautiful stride towards the fulfilment of extraordinary potential.

That victory against PSG was also especially satisfying for a Paris-born player who had failed a trial at his hometown club at the age of 11 but likes to wear the No14 as a tribute to the arrondissement in which he grew up in France’s capital city. His parents are Ivorian and, if Didier Deschamps had not awarded him his first senior cap in March, Bakayoko might have ended up playing internationally for the same country as the player he has always said he would like to resemble, Yaya Touré.

There are similarities between the styles of the two players but Bakayoko will need to start scoring regularly before any comparison becomes tolerable. But then Touré took a little time earlier in his career to be seen as an unstoppable attacking force and, indeed, once endured a patchy season at Monaco. Bakayoko’s role at Monaco even during his marvellous last season made him the least attacking midfielder in an exceptionally offence-oriented side. Bakayoko, one feels, can get even better. He could prove a spectacular addition to Chelsea if he is encouraged to add goals to his game under the relentless prodding of Antonio Conte.