Not long ago I was speaking to some Napoli fans about Lorenzo Insigne. He was born in Naples, signed for the club aged 15 and has been running up the wing at the Stadio San Paolo for nearly a decade. I put it to the supporters that, if Insigne helped the club go one better than the second-place finish they achieved in Serie A last season and Napoli finally won their third league title, it might be fitting to reward him with a new squad number. The club retired Diego Maradona’s No 10 shirt after he inspired them to two league titles in 1987 and 1990. If anyone deserved the honour of bringing it out of retirement, surely it would be local boy Insigne?

The Napoli fans responded with an unequivocal “no”. It was nothing against Insigne, they said, but rather the simple acknowledgment that no one ever will deserve the No 10 shirt because no one will ever be Maradona. Insigne will have to stick with the No 24 – his wife’s birth date.

The first shirt number to be retired from professional sport was that of the Toronto Maple Leafs star Ace Bailey. While playing in an NHL game against the Boston Bruins in 1933, Bailey was upended and landed headfirst on to the ice, fracturing his skull in the process. His injuries were so severe that doctors worried he might not survive. He pulled through, but never played professional ice hockey again. In response, the Maple Leafs retired Bailey’s No 6 shirt permanently.

La Liga could teach the Premier League about being competitive Read more

The practice of retiring squad numbers quickly spread through US sports. The New York Yankees have now retired every single number from one to 10 and they somehow managed to retire their No 8 twice – for Yogi Berra and Bill Dickey.

The idea did not catch on in football until much later. For a long time footballers did not have fixed squad numbers and instead wore the shirts 1-11 according to who was picked on the day. It wasn’t until the early 1990s, when shirts began to bear the players’ names as well as numbers, that it became necessary to fix the numbers from one game to the next. Almost as soon as squad numbers were allocated, clubs started to retire them. The frequency with which numbers are retired, and the reasons for it, offer interesting insight into the mentality of different clubs and their fans.

It is fairly common for football clubs to retire the No 12 in honour of the fans, the mythical “12th man”. None of the current Premier League clubs have retired the No 12 shirt but sides such as Bristol Rovers, Exeter City, Gillingham, Oxford United, Oldham Athletic, Peterborough, Plymouth Argyle and Portsmouth have gone for the idea. It is more common on continental Europe, where Bayern Munich, Lazio and PSV Eindhoven have gone down that route. As a gesture, it seems a bit condescending to supporters, something that requires neither imagination nor expenditure from the board.

Facebook Twitter Pinterest West Ham gave fans T-shirts this year to mark the 25th anniversary Bobby Moore’s death. Photograph: Peter Byrne/PA

A lot of numbers have been retired to show respect to players who have died tragically in their prime. Some, such as Piermario Morosini of Livorno, even did so on the pitch. This gesture acknowledges their irreplaceability: that no one else could step into the place they have vacated so suddenly. Far more intriguing, however, are the numbers retired for players who are either still alive or who died long after their retirement, such as Bobby Moore’s No 6 at West Ham or Javier Zanetti’s No 4 at Internazionale. There is something slightly grandiose about this, as if fans are commending the player to the ages, like a Viking warrior pushed out to sea on a ship with his shield and battle armour.

This is nowhere more true than in the case of Paolo Maldini’s No 3 shirt at Milan. When Maldini hung up his boots in 2009, the No 3 he wore for almost the entirety of his career was not completely retired but was instead held until one of Maldini’s sons, Daniel or Christian, could emerge from Milan’s youth system and take it.

This romantic, almost fairytale, gesture acknowledges the club’s history – Paolo’s father Cesare had also been a Milan captain – while also nodding to the future. The implication is that only someone from that illustrious Maldini line could be capable of filling that role, heirs to the throne in an almost literal sense. However, with 22-year-old Christian currently playing for Pro Piacenza in the third tier and 17-year-old Daniel still in the Milan academy, it is hard to see that No 3 shirt as anything other than another albatross around the necks of two youngsters who already have an incredible legacy to live up to.

Facebook Twitter Pinterest Roberto Baggio captaining Brescia in 2004. Photograph: Carlo Baroncini/AFP/Getty Images

The example of Roberto Baggio shows how relative the concept of irreplaceability can be. The beloved trequartista is probably most closely associated with the No 10 shirt of Italy’s national team, but that number was never retired for him. Nor was his shirt at Juventus – where he won the Ballon d’Or and his first Scudetto – or at Milan, where he won his second league title. Instead, his No 10 shirt was retired by Brescia, his final club.

This might seem odd. A cynic might think that Brescia, a club whose best ever finish in Serie A was seventh place, were merely trying to wring the last drops of glamour from its association with a player who was really out of their league. A more charitable view would be that Baggio played more league games and scored more goals for Brescia than anywhere bar Juventus and that, freed from the dressing room politics and injuries that blighted his career at bigger clubs, he was able to be truly influential at Brescia, leading the club to that all-time best league finish and an Intertoto Cup final.

Baggio was irreplaceable for Brescia in a way that he wasn’t for Inter, Juventus, Milan or Fiorentina. Retiring his squad number was a way of saying “it won’t get better than this” and it’s useless for a side with Brescia’s resources to pretend otherwise. Anyone who saw Baggio’s golazo against Juventus would be inclined to agree.

There is something unsatisfying and even anti-sporting about retiring squad numbers. A significant part of sport’s appeal it that it is endlessly renewing itself; as soon as you are crowned champions, you need to prepare your title defence because everything is reset to zero when the new season comes around. This is what keeps fans coming back over and over again, hoping that this year will be their year. It is unsurprising, then, that most top clubs have little interest in retiring numbers. To do so would be to suggest that one particular victory was freakish or unusual.

The most successful clubs want to convey the idea of endless renewal in the pursuit of excellence. Manchester United are unlikely to retire their iconic No 7 shirt and it’s the same with the No 10 at Juventus. Both clubs take pride in the long list of illustrious players who have worn them, suggesting that those shirts will continue to be worn by the superstars of the future. Similarly, when Lionel Messi and Cristiano Ronaldo hang up their boots, it would be surprising if Barcelona or Real Madrid retired their numbers. They will look to other players in the expectation that they too will enjoy outstanding careers.

Golazos galore: the 25 best goals from the golden era of Serie A Read more

Contrast this with how Napoli feel about Maradona. He is worshipped like a saint in Naples, where his image is blazoned on walls across the city. Fans regard Maradona as irreplaceable and his achievements as little short of miraculous. However, by linking their only period of success so strongly to one man, they betray the fear that there will never be another league title. If Napoli wish to win a third Scudetto, they may need to overcome these hang-ups and adopt the mentality of their hated rivals, Juventus, who view success as both a right and an obligation rather than a miracle.

In the meantime, Insigne could do worse than consider the words of one Napoli fan, who told me: “Instead of thinking about the No 10, Insigne should concentrate on making them retire the No 24.” If he and this Napoli side can win that title, the club might do just do it.

• This article first appeared on The Gentleman Ultra

• Follow Ricci Potts and The Gentleman Ultra on Twitter