Hart established himself in the Premier League in 2007, sharing goalkeeping duties at Manchester City with Kasper Schmeichel, Andreas Isaksson and Shay Given over two seasons.
Given's arrival at City in January 2009 prompted Hart to join Birmingham on loan the following campaign and he impressed after a difficult start, keeping goal as the Blues embarked on a club record 12-game unbeaten run in the top flight.
With Given having suffered a serious shoulder injury late in 2009/10, former Shrewsbury prodigy Hart was the natural successor. Meanwhile, England's goalkeeping nightmare with Rob Green and David James at the 2010 World Cup set him up perfectly for the national team as well.
From there, Hart played every Premier League game for City for the next three years, missing just 12 in six whole seasons as the number one at the Etihad Stadium. He was also part of the City side that finally broke the club's 35-year trophy drought with FA Cup glory in 2011, collected two Premier League titles, and was also a four-time Golden Glove recipient.
Cracks had begun to appear, though. Hart was temporarily dropped midway through the 2013/14 campaign after a number of high profile errors, including three against Bayern Munich in the Champions League and one which gifted Fernando Torres a latter winner in a loss to Chelsea.
After a poor Euro 2016 with England in which he was at fault for goals conceded against Wales and Iceland, incoming City boss Pep Guardiola had seen enough. Even before Claudio Bravo had been signed from Barcelona, the new coach kicked Hart to the kerb, favouring back-up Willy Caballero in the early Premier League games of 2016/17.
City fans who had idolised Hart for years couldn't understand why, but when Bravo did make the switch to Manchester from Catalunya, Hart's time was over. It was suggested that the Chilean better fitted Guardiola's tiki taka style in which the goalkeeper was expected to be a part of the passing game, but it was clear that Hart's loss of form and attitude - many questioned whether he was taking his career seriously enough - contributed to the decision.
With no place at City, Hart was left with a problem. There was no place for him at any other top or even reasonable Premier League team either - the likes of Southampton and Leicester were sorted, while Everton opted for Maarten Stekelenburg. After a noticeable drop off, nobody was willing to take a chance on Hart, considered world class by some just three years earlier.
And so he had to look abroad, winding up at Torino on loan. It was supposed to be his redemption, almost a 'f*** you' to City and Guardiola, but it could hardly have gone much worse.
Despite occasional flashes of quality, Hart was poor in Italy. An error on his debut led to a defeat against Atalanta, while by April it was reported that his mistakes had directly led to Torino conceding five goals, the second worst record of any player in the whole of Serie A. In May, two more errors resulted in Torino drawing 2-2 with Inter, and even though the club finished three places higher in Serie A that the previous campaign, it could have been so much better.
Hart's major issue, as it had been in previous years in the Premier League, appeared to be handling crosses and decision making. Intelligent Italian teams learned to target his weaknesses. "We probably didn't expect so many mistakes," were Torino president Urbano Cairo's cutting parting remarks to sum up the failed loan.
Back in England, the door at City was closed further when £34m Ederson arrived from Benfica, while, again, other top clubs were still not interested. Everton looked to the future by splashing out on Jordan Pickford, while Manchester United were weakly linked in the event David de Gea left the club to join Real Madrid. The rumour caused a stir but it was never going to happen.
Instead, Hart has found his calling at West Ham. Where Torino failed to be his redemption, this season in east London can be. It also has to be.
Hart's greatest strength has long been his shot stopping ability. At City, he was always at his best when kept busy - think back to a performance in a narrow Champions League defeat at the hands of a rampant Barcelona side in 2015, and how he played against Real Madrid in another narrow defeat in 2012, keeping the score down and giving his team a chance they didn't take.
Conversely, he's at his worst when he's out of the action. His concentration slips and it has proven costly in the past. At West Ham, a team that shipped 64 goals in 38 games, at least 13 more than nine of the 10 teams who finished above them last season, he should be busy most of the time. It is therefore Hart's chance to shine. If he does, his reputation will grow once more.
Come February or March, the rumours of a big move will start if he's had a strong season and Liverpool and Arsenal could well be in the market for a number one stopper. By the end of next season, Hart will be 31 years of age; he should be at a goalkeeper's peak and could have his route back to the top secured. But if his ongoing slump continues, who knows what