At two and a half years, Ruben Amorim’s contract as Manchester United’s manager is no resounding this-is-our-man-for-the-long-term deal from Sir Jim Ratcliffe’s football department.

It may be a sagacious move by those charged with executing the best move for the club. In versing themselves in the 20-times record champions’ recent history, Dan Ashworth, the sporting director, and Omar Berrada, the chief executive, will have noted how, since Sir Alex Ferguson departed in May 2013, none of his five permanent successors have lasted three years.

Related: Amorim is the right choice at last: now Manchester United must make it work | Barney Ronay

This points to the quicksand beneath the Old Trafford hot seat that has sucked down David Moyes (tenure: June 2013-April 2014), Louis van Gaal (June 2014-May 2016), José Mourinho (May 2016-December 2018), Ole Gunnar Solskjær (March 2019-November 2021) and Erik ten Hag (May 2022-October 2024).

What we see, too, is how the mantra repeated by the club that all would be given time to right the listing ship evaporated once the maelstrom of poor results hit.

In one of Ten Hag’s last media conferences the point was put by this correspondent that no manager had been in place for three years and that since Ratcliffe et al recognise patience was needed, the Dutchman might need five.

Ten Hag said: “There’s almost no club in the world where expectations are so high and that’s set from the era of Sir Alex and the rest of us have to deal with this. Demands [are] the highest in every process and we’re not there in every process. We so far haven’t got to challenge for the Premier League or Champions League but that’s the ambition.”

Run through every post-Ferguson failure and the same stew of managerial missteps, abysmal recruitment, losing fans’ faith and pressure from inside/outside is found.

Moyes went after 34 Premier League matches and was culled when United could no longer seal a Champions League berth – a function of internal pressure. The Scot’s major signings were Marouane Fellaini and Juan Mata – here, the dodgy recruitment. Moyes’s billing of Liverpool as “favourites” when visiting Old Trafford in March 2014 lost supporters, and came a month after the 2-0 Champions League loss at Olympiakos: a “nadir” for this writer and the starting gun that set running the external scrutiny.

Van Gaal was sacked the day after claiming the 2016 FA Cup – the first post-Ferguson trophy – because of Champions League qualification failure. “Average” is a fair characterisation of the transfers he was granted, a group who included Ángel Di María, Bastian Schweinsteiger and Daley Blind. Sideways, “anti-United” football wiped away fan backing and caused pundits and the media to question him.

Mourinho was removed 48 hours after the dire 3-1 loss at Liverpool in December 2018 amid a turf war ignited by the club’s refusal to purchase Harry Maguire that summer. And, his “respect, respect, respect” outburst to a question from this correspondent after a 3-0 home reverse to Tottenham four months before his removal was the moment the fans lost faith and seasoned United watchers started to wonder at the “Special One’s” longevity.

Solskjær’s big misstep was failing to beat Villarreal in the 2021 Europa League final: had he done this and broken his silverware drought, he might have survived the following season’s flatlining results which led to his axing in November. The Norwegian’s boom-and-bust time in charge caused near-constant speculation that the end was soon nigh. Transfer-wise, he was handed the fait accompli signing of an ageing Cristiano Ronaldo in summer 2021. And from the following mid-October, fans could not stomach the 4-2 defeat at Leicester, consecutive home humiliations by Liverpool (5-0) and Manchester City (2-0) and the 4-1 trouncing at Watford, which finally caused the trigger to be pulled.

So, after the sorry tales of these proud managers, we arrive at Amorim, who in Friday’s press release was revealed as United’s first “head coach”. This is a function of Ratcliffe’s new structure, indicates that the all-powerful manager is viewed as an anachronism and, maybe, recognises that Amorim could be chewed up before the 12-month extension on his terms can be taken.

After all, Amorim is predated by 10 appointments in the 11 post-Ferguson years, once the quintet of interim managers is included: Ryan Giggs (April-May 2014), Solskjær (December 2018-March 2019), Michael Carrick (November 2021), Ralf Rangnick (November 2021-May 2022) and Ruud van Nistelrooy (October-November 2024). Instability has become United’s unwanted culture. Those picking the XI are here today and gone far too soon.

In April Amorim dallied with West Ham but a wage demand of about €10m is thought to have put off David Sullivan, the club’s largest shareholder. Ratcliffe has granted Amorim the salary, which represents an approximate threefold increase on his €3m (after tax) pay at Sporting. He hopes to start deserving it when taking his side to Ipswich on 24 November for United’s first game under him.

Amorim suggested that on Friday, after Sporting play Estrela, the “soap opera” of his move would be over. Maybe. But, soon, life under the United microscope begins. Recently this has been a saga featuring far too many embarrassing displays and ongoing high farce. To succeed and last for three years, at least, Amorim has to move the club on.