Norman Whiteside scored in two FA Cup finals before his 21st birthday, the second a glorious winner to deny Everton a treble. He is the youngest person to play in a World Cup and hit an awesome winning goal in an FA Cup semi-final against Arsenal at the age of 17. Yet when he meets Manchester United fans, they do not want to talk about those achievements. All they want to discuss is the Norman conquest of Anfield.

In April 1988 United were 3-1 down with 10 men against possibly Liverpool’s greatest side when Whiteside came on as substitute. He roamed the green with vigilante intent, hoofing Liverpool all round Anfield and inspiring an improbable 3-3 draw. The game meant nothing in the grand scheme – Liverpool were running away with the title – but then Liverpool v Manchester United fixtures have always been a competition of their own, with an intensity that makes the phrase “bragging rights” seem far too frivolous.

After that match in 1988 Alex Ferguson said that teams left Anfield “choking on the vomit”, an early indication of his loathing for Liverpool. For both clubs the fixture has always been a crystal-clear window into the soul – the result is all important but the way it comes about is often more revealing.

In 1992, when United blew their chance to win the title for the first time in 25 years, their failure was confirmed by a painful 2-0 defeat at Anfield, in which Ian Rush finally scored his first goal against United. But the way in which they raged against the dying of the light – they hit the woodwork three times and Bryan Robson and Paul Ince played the full match despite being nowhere near fit – showed that the long-term was nothing to worry about. When a Liverpool player shouted “Fuck you!” at Ferguson after the game, he had even greater reason to come back stronger.

Louis van Gaal won his first four fixtures against Liverpool but in only one of those games – the slick 2-1 win at Anfield last season – did United hint that they might be going somewhere. That was part of a surreal month period in which they also thrashed Spurs and Manchester City but Thursday’s compliant defeat was far more indicative of the club’s health.

Before the match Jürgen Klopp called it “the mother of all games”. United played as if the fixture was the third cousin on their mother’s side, twice removed. Van Gaal is culpable but so are hundreds of others. This was the logical conclusion of an erosion in standards and values that gathered pace when the Glazers bought the club in 2005 and accelerated further when Sir Alex Ferguson retired in 2013.

The shabby manner in which David Moyes was sacked in 2014 is the best example that the problem is as significant off the field as on it. Van Gaal, a once brilliant manager who is past his best, deserves better than to be openly ridiculed. And to blame him exclusively is grossly to oversimplify a complicated story of compromise, politics and self-interest.

Gary Neville’s celebration of a Manchester United’s late winner against Liverpool in 2006 feel like something from a bygone age. Photograph: Eddie Keogh/Reuters

For United surrendering at Anfield is the most unthinkable thing of all. Or at least it was. The game stirred passion to such an extent that Ferguson once sacked Peter Schmeichel over a row that started because he thought Schmeichel’s goalkicks were too straight. The club’s identity has changed so much in the last decade that things such as Whiteside’s rampage and Gary Neville celebrating a last-minute winner in front of the Liverpool fans in 2006 feel like something from a bygone age. “The punishment was a joke,” said Neville of the fine he received as a result, “but I’d pay the money again and again to have that feeling.”

It is a feeling that many modern players would not understand. To some extent this comes from the manager, who prefers robots to humans, but there were far worse defeats at Anfield under Ferguson, the greatest manager of all. That included a 3-1 defeat in 2001 so appalling that Ferguson broke the habit of a lifetime and publicly criticised his players. “Maybe they have been here too long and take success for granted,” he said. “Liverpool worked harder than us.” There was an even tamer surrender at the Etihad in the title decider of 2011-12, when a muted United did not have a shot on target.

The difference is that, under Ferguson, such performances were generally the season’s exception rather than the rule. It is better to have one obvious nadir than umpteen contenders. United’s display on Thursday night was not surprising, never mind shocking. The players they have are not very good. They are also far too nice and bear no resemblance to perfectionist winners such as Paul Scholes, Gary Neville and Roy Keane, a man whose game face should have been a modernist painting entitled ‘Standards’.

Those players cared about the club they played for, something that is less common these days. It would be easy and entirely wrong to blame this on the reduction in British players, as Luis Suárez, Rafael da Silva and Pablo Zabaleta have shown in recent years. It was Rafael, a Brazilian full-back, who single-handedly defended United’s honour against City and Liverpool by picking fights with Carlos Tevez, Lucas, Martin Skrtel and others.

The problem is not unique to United; it is simply more acute because of what went before. There is no easy fix because the world has changed: football is a mercenary industry for players and managers, and masculinity has changed enormously in the 21st century. The strong, silent type is an endangered species, and Steve Archibald’s comment about team spirit being an illusion glimpsed in the aftermath of victory looks truer by the year.

The identity of a club comes primarily from the manager, so having somebody who stays for more than a couple of years would help. That does not necessarily preclude José Mourinho, who it is said has long planned to build a legacy at United in the final 10 years of his career.

There are obvious risks in United hiring Mourinho but the risks are even greater for him. A humongous repair job needs to be done on and off the field, just as when Ferguson came to the club. Not even a specialist in success such as Mourinho comes with a guarantee of trophies this time. But when it comes to restoring United’s identity, he does have at least one thing going for him: he really cannot stand Liverpool.