London – Watching on at Anfield as Manchester United meekly surrendered 3-1 to Liverpool in what proved to be Jose Mourinho’s last match in charge, Alex Ferguson was caught shaking his head at the sight of what the empire he built has become.

For the fourth time since Ferguson retired in 2013 after nearly 27 years in charge, with 13 Premier League titles under his belt, United are looking for a new manager.

The volatile Mourinho was largely the author of his own downfall. He leaves the world’s richest club 19 points off the top of the Premier League and with an almighty struggle just to qualify for next season’s Champions League with a top-four finish.

But his departure should sound alarm bells for United’s American owners, the Glazer family, as they struggle to find a manager capable of following in Ferguson’s footsteps.

The fiery Scotsman signed off by winning the league. In the five years since, United have not even been in contention to win the title.

Replacing one of the all-time greats was never going to be an easy task but even Ferguson, who also led United to two Champions League crowns, five FA Cups and four League Cups, would never have dreamed it would prove such a poisoned chalice.

As a fellow Glaswegian whose relative success on a limited budget at Everton evoked memories of Ferguson’s breakthrough years with Aberdeen, David Moyes apparently had the skill set and background to follow his compatriots template in Manchester.

But after Ferguson anointed him as his hand-picked replacement, Moyes proved completely out of his depth and lasted just 10 months of his six-year contract.

Moyes’s penchant for conservative tactics, dour training sessions and a lack of man-management skills might seem familiar to members of the current United squad, who grew sick of Mourinho’s acerbic personality.

By the time United were ruled out of qualifying for the Champions League, the writing was on the wall for Moyes, whose sacking in April 2014 made his the shortest United managerial reign for 82 years.

Autocratic Dutchman Louis van Gaal was also a poor fit despite his impressive pedigree with Barcelona and Ajax. His football was too one-paced and predictable for fans fed on Ferguson’s aggressive approach for so long.

Returning United to the Champions League with a top-four finish in his first season bought Van Gaal some time, but the only standard that matters at Old Trafford is winning the title.

When they laboured to a fifth place finish 12 months later, even United’s FA Cup final win against Crystal Palace was not enough to spare Van Gaal.

Mourinho’s self-proclaimed status as a serial trophy winner made him the obvious choice to take a role he had long regarded as his dream job.

But the siege mentality that helped Mourinho inspire his players to remarkable success at Porto, Chelsea and Inter Milan was no longer such a convincing act for the pampered millionaires that inhabit the Old Trafford dressing room.

Although Mourinho won the League Cup and Europa League in his first season, United finished a dismal sixth in the Premier League.

It did not help that Mourinho’s dour game-plans in a trophy-less second season contrasted so sharply with Pep Guardiola’s stylish and successful Manchester City side, who romped to the title with a record 100 points.

And at Liverpool, Jurgen Klopp had woken a sleeping giant and put them in contention for a first league title since 1990, adding defensive steel to attacking flair.

Guardiola and Klopp were both on the market in the post-Ferguson era and passed United by.

The club stated on Tuesday that time will be taken to find a successor, with a caretaker put in charge for the rest of the season.

But there are concerns over who will make that decision, with the club increasingly obsessed with commercial interests rather than winning on the pitch.

“There’s a multitude of issues, it’s more complex than the manager getting the best out of the players or not being backed. It’s a deep problem, it needs resetting, the whole club needs resetting,” said former United captain Gary Neville.

“Five years ago, two huge figures (Ferguson and former chief executive David Gill) left that football club, two figures that had great knowledge of the game.

“What happened was the financial and commercial people, that are fantastic at their jobs, were put in charge of the football side of things and they are not competent enough to do it.

“They have to now hand it over to people that are good enough to run the football side of the club.”