Manchester United fans have a song about Michael Carrick, which includes the words 'hard to believe it's not Scholes'. The lyrics are apt. In the media-driven world of modern football, Carrick is one of the most understated individuals you can find. He didn't court publicity as a player - to his detriment some might say - and didn't go out of his way to make headlines as a manager at Middlesbrough.

When he left Boro, many wondered if he would be seen in the dugout again. Now, the lure of United has taken him to the brink of a return. He is expected to be in charge for Saturday's derby against Manchester City. What is it about Carrick that United have found so attractive? And can he sort out the mess that has enveloped Old Trafford?

Carrick has not been a stranger to Manchester United this season. Ironically, alongside Darren Fletcher, who he is the leading candidate to replace as interim manager, the 44-year-old played for the club in a legends game at Celtic in September. In November, Carrick was at Old Trafford to support the Manchester United Foundation's annual sleepout, which raised more than £30,000 for its community projects.

More recognisably though, his link comes through the 464 appearances he made in a 12-year stint as a player, winning five Premier League titles, an FA Cup, three League Cups, a Champions League, a Europa League and a Club World Cup. Remarkably, he never once won a Premier League Player of the Month award and only made the Team of the Year in 2013. He won 34 England caps but despite making the 2006 and 2010 World Cup squads, only made it onto the pitch in a single game.

Yet, if he was asked about whether he felt underappreciated, Carrick would tend to shrug and say, 'that's football'. He didn't change as a manager. Always polite and friendly but not generating headlines for the sake of it. His exuberant celebration after a 3-1 win at Sheffield United in February 2023, triggered by some pre-match needle between the sides, is remembered because it was so out of keeping with Carrick's normal behaviour.

One pre-match dressing room chat was recalled in gathering background on Carrick for this article. With players on the pitch completing their warm-up, many managers want to be left alone in silence. Others obsess with their tactics board. On this particular day, Carrick engaged in a chat about the old TV remotes. "Never too up, never too down," says the source. "That is Michael. He doesn't waste 10 words when one will do. At Middlesbrough, everyone loved him." Everyone apart from the fans in the end.

When Carrick arrived on Teesside in October 2022, he resurrected a club flirting with relegation and did so by delivering exciting, winning, possession-based football. After losing his first game against Preston, Boro won 16 out of their next 22 league matches. Carrick deployed a number of different formations, including three at the back at times, and scored three goals or more on 11 occasions.

When they beat Preston in the return game at the Riverside on 18 March, they were three points off automatic promotion. Striker Chuba Akpom was on his way to 29 goals for the season and a return to the Premier League after a six-year absence was on the cards. But Boro's form deserted them at the wrong moment. They won two out of their last eight games, missed out on automatic promotion by 16 points and were beaten by Coventry in an attritional play-off semi-final that produced one goal in two games.

It never got better than that for Carrick at Boro, even though he lasted two more seasons. The first of those never recovered from a rotten start, when they collected two points from their opening seven games. The second lacked consistency and five straight defeats from January into February ensured there was no late run to the play-offs.

On the plus side, there was a run to the EFL Cup semi-final in 23-24, where Boro were eventually beaten by Chelsea. Carrick could also point to the sale of Akpom to Ajax in the summer of 2023, five key loan players not returning and Morgan Rogers' £15m exit to Aston Villa in February 2024 as mitigation for not hitting the same heights, as Boro profited from the work he had done developing players. Supporters didn't see the situation in quite the same terms.

In the end, they felt he was too wedded to a 4-2-3-1 formation they did not believe was working. 'No Plan B' was a familiar criticism. Carrick's response of 'I'm not going to change the style of play, it is what I know and what I believe in. We wouldn't be good coaches if we suddenly went down a totally different route' has echoes of Ruben Amorim.

Yet it is clear Carrick can see the benefit of tactical switches. On Match of the Day 2 in October, summing up United's win over Brighton, Carrick explained how his old club had achieved their success by forward players dropping and Luke Shaw pushing forward, condensing the space midfield pair Casemiro and Bruno Fernandes were being asked to cover.

"In the end, it's a numbers game and a space game," Carrick explained. "You can see there is something building with the connections." Carrick has been United's manager before. He filled the gap between Ole Gunnar Solskjaer's dismissal in November 2021, stepping up from head coach before leaving when Ralf Rangnick arrived. His three games at the helm included two wins and a draw. One of the victories was a 3-2 success against Arsenal.

It was a link to a glorious past – as Ryan Giggs, Solskjaer and Ruud van Nistelrooy provided, in addition to Carrick himself, when they were asked to step in on a temporary basis following previous dismissals. Carrick will start with unqualified backing from the stands – although through the last 13 years since Sir Alex Ferguson's retirement, United fans have never become mutinous against the man in the dug-out. Their ire has been reserved for the ownership.

As he finished his short stint, Fletcher declared the aim for the remainder of the season should be Champions League qualification. If Carrick delivered that, he would surely have a claim to get the job on a permanent basis. Should United miss out on Europe completely, would the gaping hole in the club's finances allow for a big-name replacement in the summer? These are questions for the next few weeks and months. There are more pressing issues at hand. Whatever it was Amorim was constructing, the project has now been abandoned. Now Carrick is expected to be given the plans to see if he can come up with an alternative design.