What if it wasn't David Moyes' fault? Does Manchester United's decline go much deeper?

A man on the concourse at Piccadilly Station swayed and laughed as he staggered towards the upstairs bar.

“Bring back Davie Moyes,” he chanted in beery sarcasm as he weaved around startled Japanese tourists in their half-and-half scarves.

Others voiced similar themes. “We’re sh** and we know we are,” a knot of young men in their new red shirts yelled out.

Everywhere, there were fans with wan smiles trying ­desperately hard to look on the bright side.

But after Saturday’s 2-1 home defeat to Swansea meant the reign of Louis van Gaal was born under a bad sign, a darker fear lurked beneath the laughter.

What if it wasn’t just David Moyes after all? What if it wasn’t just one bewildered manager failing to cope with the demands of a club the size of United?

What if getting rid of Moyes isn’t going to be the panacea they thought it would be?

What if Van Gaal can’t just flash his charisma, snap his fingers and bring the magic back?

What if it’s deeper? What if, as the Republik of Mancunia website asked yesterday, an isolated season of post-Ferguson misery and Moyesian confusion seeps into long-term decline?

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Well, United are not at that stage. Not after one opening-day defeat, even if it was against a modest Swansea side.

They were heavily depleted by injury, for one thing, forced to start with young prospects like Tyler Blackett and Jesse Lingard.

Still, the idea a run of easy early fixtures would catapult them straight back into the title race is already shot to pieces.

The reality is the side Dutchman Van Gaal fielded would have been embarrassed by Manchester City or Chelsea.

BT pundit Steve McManaman rated it the worst United line-up he had seen for more than 20 years. Alongside him, Paul Scholes did not disagree.

Scholes pointed to a lack of quality in midfield. Others pounced on uncertain defensive performances from Phil Jones and Chris Smalling.

Both were right and it is ­inevitable the focus will switch back to the transfer acumen of United executive vice-chairman Ed Woodward.

Because so far this summer, rather than closing the gap on the rest of the leading clubs, United allowed it to widen.

Fifty-two days have elapsed since they last signed a player and they have let City and Chelsea, in particular, steal a march on them.

Woodward’s stated intention was to get business done early this summer, like in the old days under Sir Alex Ferguson.

Whatever the reason, that did not happen. Instead, they left it to the last minute to try to claim reinforcements.

Sure, they signed Luke Shaw and Ander Herrera earlier in the summer and both are highly promising young players.

But neither is of the calibre of, say, Toni Kroos, who was ready to join but was then allowed to sign for Real Madrid.

Shaw and Herrera are not going to propel United back to the top of the table. They are not marquee signings.

United are fond of calling themselves the biggest club in the world. Yet compare their ambition with that of Real Madrid, Barcelona and Bayern Munich.

United are not even close. They are not just in danger of falling further behind in English football; they face losing touch completely with the European elite.

The reality is the current predicament is the product of years of under-investment by the Glazer Family that was camouflaged by Ferguson’s strengths. That has to be reversed if they are to become the pre-eminent power in the English game again.

No matter how fine a coach Van Gaal is, no matter how good he is at getting the maximum from his players, the gap in the raw material possessed by United and teams such as Chelsea and City is growing too wide.

Woodward must act fast and boldly. Otherwise, another season of mediocrity beckons.

There are rumours a stunning transfer coup is about to happen. Some whisper the name of Bastian Schweinsteiger. Others Arturo Vidal, or Daley Blind.

But United have been talking a good game for some time now, just as they did last summer. Gary Neville said in his newspaper column on Saturday he believed two players would be signed before the end of the month.

The need for them became starkly obvious after Saturday, although Wayne Rooney dismissed McManaman’s ­observations. “It’s always a bigger story when Manchester United struggle and we saw that last season,” said Rooney, who scored with a close-range bicycle kick.

Either side of that, though, goals from Ki Sung-Yueng and Gylfi Sigurdsson, the product of defensive errors from United, gave Swansea the advantage.

“You’re going to get ex-players going over the top,” Rooney said of McManaman’s barbs.

“We have to make sure we’re successful, make sure last season was a one-off. It was a disaster.

“We’re not out to prove people wrong. We’re out to win things for ourselves, the fans and this club.”

Maybe not but if United do not make significant acquisitions in the transfer market in the next fortnight, a bleak landscape stretches ahead.