There is no doubt Manchester United’s move for Radamel Falcao came as a jolt for the football world, with all the questions it leaves about how Louis van Gaal can possibly shoehorn everyone in, Galáctico-style, but the truth is that the people in charge at Old Trafford decided long ago that a frontline including the considerable talents of Wayne Rooney and Robin van Persie was not dynamic enough for a club of their ambitions.

David Moyes was the first person to identify the issue and initially thought Edinson Cavani had the directness and penetrative qualities to give the team a more vibrant attacking edge. Moyes told Ed Woodward, United’s chief executive, during one strategy meeting that the Uruguayan would “score goals for fun”. A meeting was arranged with his agent, Claudio Anelluci, and United were given the firm impression Cavani wanted it to happen. However, Moyes watched Cavani three times after the turn of the year and he was poor every time. Paris Saint-Germain wanted £65m and Moyes, with deficiencies in midfield and defence, decided the money was better spent elsewhere.

What perhaps comes as a surprise is that Van Gaal still wanted another forward, even though Ángel di María signed from Real Madrid for a British record fee last week and it did not need forensic analysis to realise United’s squad were already top-heavy with attackers but conspicuously short in defence.

Yet United acted swiftly and decisively when Jorge Mendes, the agent representing Falcao, got in touch on Sunday. Mendes, whose other deals this summer include Di María, James Rodríguez, Diego Costa and Eliaquim Mangala, has struck up a strong relationship with Woodward, to the point of regularly texting him with family photographs. What followed, by modern standards, was an agreement of uncommon speed that demonstrates, again, United’s determination to spend their way back to the top of their sport.

Where Falcao fits in – or, rather, who drops out – is another matter entirely and it is not being unduly negative to wonder if United have jumbled priorities, given the imbalance it leaves Van Gaal, with a pick of superstars up front but a defence that will always encourage opponents.

Van Gaal has never been afraid to leave out players who previously considered themselves mandatory first-team picks and, ordinarily, Rooney’s place would have to be vulnerable. Yet Van Gaal has just given him the captaincy and one of the reasons he gave for making that decision was he envisaged the player, who has just clocked up his 10th anniversary at Old Trafford, being involved every week.

Van Persie is firmly established as one of the manager’s favourites and maybe that means it will be Juan Mata who has to suffer the consequences. Mata could probably be forgiven for wondering where all this leaves him – and let’s not forget how it might affect Adnan Januzaj either. Nobody should doubt Januzaj has the gifts to go to the highest levels of his profession – described by one senior football man at Old Trafford as a “young Johan Cruyff” – but even someone with his ability and self-belief might be wondering how the past week will impinge on him.

Before anything, Van Gaal has to decide whether to stick with his 3-4-1-2 formation after its conspicuous lack of success so far or switch to a more conventional system, most likely 4-3-3, that might be better suited to his evolving squad.

A front three of Di María, Van Persie and Falcao would be a daunting prospect for even the most accomplished defence and perhaps this is now the point in Rooney’s career when he and his manager have to start giving more thought to him dropping into midfield.

Moyes was convinced it was inevitable at some stage because Rooney had lost the burst of pace that made him such a whirlwind of a player when he was younger and the former manager would privately admit he should have been emboldened enough to do it more times last season. Moyes was also under the impression that Rooney was more receptive to the idea than people might realise, in contrast to the days when the player would openly complain if he were shifted from his usual role in central attack.

There was, however, a feeling among the coaching staff that Rooney needed to learn the role and was not a natural. More than anything, they were concerned that Rooney was not particularly good at short passes, in the way that Michael Carrick and Paul Scholes would give and go. They knew Rooney could play the killer pass. The issue was whether he knew the right moment to look for that pass.

In the meantime, Daley Blind and Ander Herrera have joined the club as upgrades to Marouane Fellaini and Tom Cleverley. Carrick is still to return from injury, with Darren Fletcher in reserve, and there is finally the sense that United have started to fix some of the midfield issues they have neglected too long.

It is in defence where United have a lopsided look and there are no apologies here for repeating that, before even thinking of adding Falcao to the payroll, they surely ought to have done more to improve their backline when they had so much advance warning Nemanja Vidic and Rio Ferdinand were on their way as well as ongoing concerns about the amount of time it was taking for Chris Smalling, Jonny Evans and Phil Jones – all too erratic and too injury-prone – to fulfil their potential.

“Potential”, Sir Alex Ferguson used to say, is a dangerous word. “I kept hearing about the potential of this guy when I first came to United,” he once said of Peter Barnes. “Everyone was telling me he had great potential – but he was 30 years old. It’s made me dislike the word.”

Evans was marked three out of 10 in the Manchester Evening News for his performance against MK Dons last week and, at 26, it feels as if we have been talking about his potential since his loan spell with Sunderland six years ago. To put it bluntly, he needs to get a move on.

Welbeck is another one who has frequently tempted us to believe he can shine consistently at the highest level but never quite done enough to remove all the lingering question marks. Welbeck, on form, can be a formidable opponent, with that long stride, upper-body strength and direct running. Yet his defining moment last season came in the Champions League quarter-final at home to Bayern Munich when he ran through the opposition defence to face Manuel Neuer.

What is not widely known about that night is that United’s scouting staff had noticed a possible flaw in Neuer in these positions, whereby he would often leave the ground as he spread his body, almost Schmeichel-esque.

Welbeck had been instructed that if this moment arrived he should keep the ball low. He did not listen. He tried a chip and got it horribly wrong. Neuer made the save and United, ultimately, went out.

It was three weeks later when it came out Welbeck had asked to leave, frustrated by his inability to win a regular starting place and not sure when it would ever change. Mata, one suspects, might be experiencing the same kind of insecurities over the coming months. Januzaj, too. Yet that will always be the way of big clubs and at least United can be certain now that they still appeal to category-A footballers. The “Gaalacticos”, you could call them. It is just a pity for Van Gaal, perhaps, that they all occupy roughly the same positions.