Thankfully Davide Santon didn’t listen to Marco Materazzi. “If you don’t go to the 2010 World Cup Cup you should turn to the balcony and throw yourself off,” advised his Inter team-mate late in the 2009 season. If Materazzi was joking, in his own inimitable style, about the balcony then his suggestion that Santon should be on the plane to South Africa was a very serious one. He expected the full-back to not only be in Marcello Lippi’s squad but a key member of it within a year’s time.

He was not alone. Only a few weeks had passed since Santon’s Inter debut, but already the hype around this tall, lean, athletic kid from Portomaggiore was threatening to get out of hand. Italian teams have traditionally been reluctant to show faith in teenagers yet already this 18-year-old had gone from making his bow in the Coppa Italia to becoming a fixture in José Mourinho’s starting XI. One former coach described him as the “white Maicon”. Mourinho himself settled for “a phenomenon”.

Barely a month on from his debut there he was, lining up against Manchester United in the Champions League and charged with keeping Cristiano Ronaldo in check. The first leg at San Siro finished goalless, with Ronaldo so frustrated by Santon’s diligent tracking that he wound up switching flanks. “I was impressed with Santon,” conceded the Portuguese forward after the game. “He is a fantastic footballer.”

Although half the season had elapsed before Santon made his bow, he managed to make 16 league appearances before the end of the campaign, collecting a Serie A winner’s medal in the process. He made his Italy Under-21 debut in March and already by the summer it was time for his first full international, a friendly against Northern Ireland in Pisa. “I always thought he was a predestinato (a person who is predestined for great things), and now that I’ve seen him in real life I can confirm that is absolutely the case,” said Lippi as he confirmed that Santon would start the game.

Italy went on to win 3-0, and Lippi had further words of praise for the player in private, though he also had a warning. “He told me I had done well because getting into the national team was very difficult,” said Santon. “But staying here is even harder.”

What Lippi didn’t mention was that the same could be said for playing at a team like Inter. Less than two years on Santon has slipped so far down the pecking order at his club that he was sent out on loan to Cesena in January, a makeweight in the deal that brought Yuto Nagatomo to the club. Santon may have returned to the national team, after a year’s hiatus, but it is far from certain that there will be a space for him at Inter next season.

The fall from grace has been shockingly swift. Santon was called up for two further international friendlies over the summer of 2009 but when he returned for the new season he found himself out of favour with Mourinho, relegated to the bench in favour of Cristian Chivu. When he did play suddenly he appeared timid, shorn of his former confidence.

Matters came to a head in late October, Santon fleeing San Siro in tears after a nightmare performance against Palermo. Brought on at half-time by Mourinho with Inter 4-0 up, Santon played extremely poorly as Palermo pulled it back to 4-3. Diego Milito would eventually score a further goal for Inter, ensuring them all three points, but Gazzetta reported that Mourinho’s dressing room deconstruction of the full-back’s performance had been scathing. “These were tears of rage,” they noted. “Not sadness.”

There were those who accused Mourinho of being too harsh on the player, and it was certainly true the manager had reacted furiously when he caught wind of Santon’s suggestion early in the campaign that he might have to go out on loan in January in order to sustain his hopes of making the World Cup. But it was also clear that the player’s form had slipped.

Santon himself suggested this might be a consequence of a constantly changing role. When Mourinho had first thrown him in at left-back he found himself in an entirely unfamiliar role, having spent much of his time in youth football as a wide forward before recently converting to right-back. He took to it quickly, however, and had made the position his own, but now was simply being asked to fill whatever gap needed plugging on a given day. The lack of certainty undermined him.

Even if Mourinho could have handled the player better, it is also true that the player made little impact on either of his successors. Injuries limited Santon’s availability at times but Rafael Benítez certainly had the opportunity to give him a lot more than the five starts he got in all competitions. He managed a total of 48 minutes in three league games under Leonardo before being loaned to Cesena on the final day of the transfer window.

Having been so keen to find first team football a year earlier, this time Santon was reluctant to leave. Cesena would be a big step down for one who had, despite his repeated insistences that he didn’t let such talk go to his head, admitted being thrilled at suggestions he could become Inter’s answer to Paolo Maldini. This too, though, became a stick to beat him with. After Santon failed to impress during his first few games at Cesena, there were accusations in the local press that he was aloft, unwilling to muck in for the cause.

Such words stung for a man who had always considered himself to be down-to-earth, untainted by celebrity status – one who despite his young age is rarely seen in nightclubs or bars and one who given time off would always choose to rush home for his mother Renata’s lasagna and a quiet day fishing with his father on the river Po. As he pointed out to reporters, before joining Inter at 14 he had spent five years in far less luxurious surroundings in Ravenna’s youth set-up.

But there are those who see the fact fact that he should take such words to heart at all as the greatest problem Santon has. There is no doubting his physical gifts, yet there is concern that he is too easily affected by criticism, and in turns allows minor set-backs to become major catastrophes in his own mind.

The story of the day he was signed for Inter is perhaps revealing. Santon had just scored a goal and played magnificently as captain of Ravenna’s youth team. He knew the scouts had been watching and should have been on top of the world, but instead as he walked off the pitch he stepped in two large cow pats, covering his brand new boots in dung. He was, in his own words, “inconsolable”. Only much later did he manage to rewrite the narrative in his mind, deciding that this must have been a good omen.

In reality, of course, it may just be that Santon is simply a young player, prone to dips in form like any other, and one whose career has been disrupted by a number of niggly injuries over the last two years as well. He he has shown improvement since arriving at Cesena (his average match rating in Gazzetta since the move has been 5.7/10), and there are rumours of big clubs preparing bids for the summer.

Cesare Prandelli, coach of the national team, has shown his faith by handing Santon two caps since he replaced Lippi in the summer. It is probably safe to say he won’t be throwing around the word “phenomenon” for the time being, but there is time yet for Santon to prove that he is still destined for greater things.

Paolo Bandini covers Italian football for guardian.co.uk and Astro SuperSport, as well as The Score. You can follow him on Twitter @Paolo_Bandini.