Three at the back is rubbish, and everybody knows it. The fans know it; witness the chanting from the away end at Loftus Road, a couple of thousand of them raised their voices in song, demanding a 4-4-2. Gary Neville knows it; speaking last night on Sky, he was dismissive of the formation:

They haven't been taking risks in the 3-5-2 system [...] I'm not a fan of 3-5-2. When you play that, you end up with your centre backs being the free men and that becomes a careful option, then it kicks into your mentality: 'I've always got a safer pass.'

And Louis van Gaal knows it.

I know in advance when we play with four midfielders in a diamond that we create more chances. But then the balance of the team is also weak. And you see it because we have created chances but also Queens Park Rangers have, and we have to decide every week how to play. That's the question.

So why does he keep doing it? Stubbornness has been suggested, and that certainly fits with his general demeanour and reputation. He knows it hampers United in attack, and what could be more stubborn than a manager deliberately sabotaging his own team's attacking prospects? What, in fact, could be more stupid?

Working on the assumption that even if Van Gaal is stubborn, he isn't stupid, we have to acknowledge that since he knows about the downsides, he's willing to accept them. That he thinks they're worth it, in pursuit of the upsides. What, then, are those upsides? What is he after?

Defensive solidity seems the obvious solution — no, no, stop laughing. While the idea that this team might be considered defensively solid is a hilarious one, while the rotating cast at the back has been both injury-blighted and buffoon-infested, and while they've been alternately painful and comical to watch, Manchester United have somehow conceded the third fewest goals in the league. They may look like berks, and they may fall over a lot, but they're are a better defensive side than they appear.

Partly that's been down to David de Gea, who has been excellent. Yet it's not as though he's been needing to make extraordinary save after extraordinary save. He's made plenty of good ones and several brilliant ones, but while at time's he's looked like a player rescuing his side, most of his performances are precisely what you'd expect from what he is: a world-class goalkeeper in good form. And in any case, for the nerdy among you, United have only conceded the fifth-fewest shots-per-game, which suggests that something useful — or at least, something not too harmful — is happening in front of De Gea as well. It's not all down to the pulpo in nets.

Van Gaal's personal conversion to three at the back came just before the World Cup, with the Netherlands. And while the injury sustained by Kevin Strootman is generally identified as the reason, that was only part of the consideration. He was also, as Jonathan Wilson wrote in the Guardian, at informed by a certain lack of quality and experience among his central defenders:

Kevin Strootman, who had been key to his midfield, was badly injured in a friendly away to France in which Bruno Martins Indi was tormented by Karim Benzema [...] Troubled by his defenders' ability to handle one-on-one situations, Van Gaal went to watch three of them play for Feyenoord against PSV Eindhoven. They lined up in a 3-5-2, the extra man in the middle at the back meaning one-on-one situations were minimised, and that, he realised, was the answer.

We know — or at least, the papers assure us — that Van Gaal wants a dominant, top quality, ball-playing central defender. We think — or at least, the papers insist — that he wants Strootman. But in the absence of both, it shouldn't be mysterious that he's sticking to his solution. That he's making do: that Di Maria's potential pace on the break is preferred to his ability to break from between the lines; that Rooney's passing weaknesses are to be accepted in midfield; that three dodgy central defenders are better than two. That United are by design, or at least by acceptance, a bit rubbish at some things.

This is not the United Way, of course; United are meant to be quick, aggressive, and ultra-attacking, and should set up accordingly. That's the way Matt Busby played; that's the way Alex Ferguson played (well, if you ignore all the times he didn't). But there are moments when ideology is everything, and there are times when, perhaps, that has to wait while a team who finished seventh last season, and who lost an awful lot of experience over the summer, have one or two leaks plugged. Van Gaal has always claimed to love to attack, but presumably he loves to work as well. There are instructive lessons for any new manager to the Premier League in the story of Andre Villas-Boas, who rode his principles and his high defensive line all the way to a P45.

Fans of cricket will be aware of a curious phenomenon that affects recently-retired players. As soon as they move from the field to the commentary box or to the newspapers columns, they suddenly become noticeably more daring in their views, counselling the onfield captain to pursue the aggressive declaration, to put in a couple more close fielders, to try to chase down the unlikely target. The balance of risk and reward is skewed by a certain distance from the situation.

The same is true with much of the criticism of Van Gaal: while understandable, it comes from a position of wanting to see something watchable — or, more nobly, something ideologically correct — as opposed to needing to do what is effective, or safe. So much of life is about choosing between two or more flawed options, and in the circumstances in which Van Gaal finds himself, it's hard to view the decision to pursue the safer option too harshly. Teams can play badly in any formation, of course, but playing badly, or playing carefully, in a 3-5-2 is safer: there's more possession, there's another defender. The control is greater.

It would be great if Van Gaal felt able to play with four at the back, with flying wingers, with United pouring forward in wave after red wave of giddy attacking fervour; if he thought United could go out and batter games into submission before killing them off. But it seems that he doesn't, however much we (and perhaps he) might like him to. And he does have evidence as to why that might be a bad idea: the one thing that must absolutely not be allowed to happen again this season is a repeat of that Leicester game, where United lined up with four at the back, scored three, generally played well, and then melted into the grass while Jamie Vardy — Jamie Vardy! — ran riot.

A freak result, perhaps. But you can understand why Van Gaal isn't willing to risk his first season on that fact, and is happy to embrace sterile domination and muck his team up instead. Things might have been different had the right defender been available over the summer, but that's speculation, and for all that United spent an absolute fortune, nobody is pretending that their squad is entirely satisfactory. As things stand he is currently on course to finish in the top four and qualify for the Champions League, which is what he was brought in to do.

In doing so, he may well be robbing us (and himself) of a few more goals, a bit more excitement, a few surging Di Maria runs, perhaps even another point or three. But if your reputation, your job, was in the hands of Chris Smalling and Jonny Evans, can you honestly say you'd be happy entirely happy leaving it with them? That you wouldn't ask somebody else to go and keep them company? Just in case?