Something very strange is happening at Old Trafford. It not so much that the grumbling is growing louder, despite Manchester United sitting fourth in the table having lost only twice in the league since the turn of the year, it is who is lined up on either side of the debate. On the one hand, unconvinced by a string of scratchy displays, is a section of the media and public arguing that the spectacle needs to improve. On the other, demanding we look at the results, is Louis van Gaal, a coach who for a quarter of a century has been dogmatically insisting that aesthetics are vital to football and that journalists and fans never look sufficiently at the process.

It is easy to be hasty and among modern football’s worst faults is its lack of patience. It is chastening to think that in the modern world, Herbert Chapman, Don Revie, Bill Shankly and Brian Clough – twice – probably wouldn’t have survived long enough to build their great sides. The example of Sir Alex Ferguson taking almost four seasons to win a trophy looms over United. It is also true that Van Gaal, at 63, is significantly older than any of those empire builders but, still, if anybody has a track record that demands another season to sort out things, it is Van Gaal. In that regard, he created problems for himself, first by insisting it would take three weeks for his philosophy to take hold, then three months and is now asking to be judged next season.

Quite what that philosophy is is also in doubt. That is not an issue of the regular changes of formation – as Van Gaal has made clear the philosophy is not the formation but is enacted through the formation – although United seem to have reached the point now where the constant switching looks less like useful flexibility than debilitating indecision. Rather, it is an issue of Van Gaal himself changing. The fundamentalist has begun to question himself – and the result has not been an unqualified success.

The early Van Gaal was a man steeped in the traditions of total football. At Ajax his system was recognisable as a development from the style that had been played at the club since the mid‑60s. The focus was on possession and the shape was a basic 4-3-3, although one of the central defenders often stepped up into midfield to make a 3-4-3, while his use of two deep-lying midfielders – Edgar Davids and Clarence Seedorf – as part of the central triangle meant the shape could resemble a fluid 4-2-3-1.

Ajax 1995 (v Milan, Champions League final, 24 May). Illustration: Guardian graphic

Where Van Gaal was seen as radical was in the slight tweaks he made, which led to him being dismissed as mechanistic by his critics. He recognised that a No10 had to contribute defensively, he acknowledged that in the modern game the central defender was as much of a playmaker as the man who played at the front of midfield, he was more concerned about how his centre-forward helped link the play than how many goals he scored and, perhaps most controversially, he urged his wide midfielders not to advance beyond their wingers for fear of being left vulnerable to counterattacks. His sides pressed hard and, having won the ball, sought to shift the ball quickly from front to back – they probably played a lot of long balls, if “long ball” is understood by Opta’s definition of a pass of more than 25m.

At Barcelona the philosophy didn’t change; in fact, if anything, Van Gaal became even more set in his ways. His goalkeeper had to be able to use his feet and pass the ball out from the back, and he ostracised those, such as Robert Enke, who couldn’t play like that. Every player had to have sufficient dynamism to fulfil their defensive responsibilities, which led to friction with Rivaldo, Giovanni and Sonny Anderson. When Van Gaal was introduced to the new signing Juan Román Riquelme, he presented him with a baby-sized Barça kit for his new-born son and said: “He’ll need it more than you will.” He knew his own mind and, at the height of his self-confidence, didn’t mind offending stars to implement his philosophy.

However, the failure with Holland to qualify for the 2002 World Cup, when he often used a more overt 4-2-3-1, the difficult second spell at Barcelona and the falling-out with Ronaldo while sporting director of Ajax, all left their mark. A decade ago, nobody wanted Van Gaal. His time at the summit of the game seemed to have run out. He ended up at AZ Alkmaar and there, he quickly realised, his principles had to be amended. A team of their resources couldn’t play a possession-based 4-3-3, or even a 4-2-3-1.

It took four seasons for Van Gaal to be fully effective, four years for him to hone his approach, but in 2008-09 he got it right. AZ played a 4-4-2 but that was less relevant than how they played it. They sat men behind the ball, they absorbed pressure and they used the long passing of Stijn Schaars, operating just in front of the back four, to release the two rapid forwards, Mousa Dembélé and Mounir El Hamdaoui. Van Gaal called that league title, beautifully unexpected as it was, “my little masterpiece”; he had learned the joy not only of rapid transitions but of an approach based almost entirely on counterattacking. That was to have profound consequences.

AZ Alkmaar 2009 (v ADO, Eredivisie, 4 April). Illustration: Guardian graphic

It is possible that had Van Gaal not lost millions of pounds in the Bernie Madoff Ponzi-scheme scandal that he might simply have stayed at AZ. His personal ambitions seemed to have changed and he appeared quite happy as the unchallenged dictator of Alkmaar. When Bayern approached him, though, financial circumstance meant he couldn’t say no. Perhaps, however, some of the reforming zeal had gone from him and he no longer felt the need to teach the world how to play. The AZ effect could be seen in his approach in Munich: the 4-3-3/3-4-3 was gone and replaced by a clear 4-2-3-1, a true holding midfielder in Mark van Bommel adding a level of security and caution that the Van Gaal of the 90s would probably have scorned. There was certainly no doubting his self-confidence and he was sacked after 21 months, less for results on the pitch than for having upset too many people off it.

The Van Gaal who took over Holland in 2012 was not the same Van Gaal as the one who had quit the job a decade earlier. An element of pragmatism had crept into his philosophy; he was not the idealist he had been – and his idealism, it should be said, was always regarded by purists as a pragmatic, even mechanistic, interpretation of the ideals of total football. “I sometimes suspect myself of being more interested in ‘playing the game well’ than in ‘winning,’” Van Gaal wrote in his 2009 book Vision. Not any more.

Even if Van Gaal had been edging to a new interpretation of football, though, the 2-0 defeat by France in a friendly last March came as a jolt. In part, his rethink was forced upon him when Kevin Strootman, the linchpin of his midfield, suffered knee ligament damage. But it was more than that: his defenders, he decided, couldn’t cope in one-against-one duels and that meant he had to try to ensure there was always an extra man to cover. Watching Feyenoord – managed by, irony of ironies, Ronald Koeman – beat PSV, he decided to switch to a system with three central defenders for the World Cup. That was a truly astonishing step: Van Gaal, at 62, decided to use a formation he had never previously used, one that embodied a style he had previously embraced only tentatively, and that at AZ. It was a recognition that, even when he wasn’t managing a minnow, he couldn’t always impose his philosophy on the world.

Was it successful? The 5-1 victory over Spain overshadows all else and was a genuinely extraordinary performance, even if Spain contributed to their own downfall – and even then, David Silva’s miss just before Robin van Persie’s equaliser was decisive; would the Dutch really have come back from 2-0 down? But what else was there? An unconvincing win against Australia, a ground-out victory against Chile that led to a tetchy post-match exchange about the nature of “attacking” football, a hard-fought win against Mexico, a penalty shootout success against Costa Rica and a torpid semi-final against Argentina.

Holland 2014 (v Spain, WC, 13 June). Illustration: Guardian graphic

On the one hand, Van Gaal took an unfancied side to the semi-finals, changed the game against Mexico with a team-talk in a drinks break, and had the audacity to substitute his goalkeeper before the penalties in the quarter-final. On the other hand, other than one startling victory, his side never really took off and even if you credit the introduction of Tim Krul for the penalties as a masterstroke, it cannot disguise the fact that in 120 minutes, the Dutch rarely looked like breaking down Costa Rica. As so often with World Cup campaigns, short as they are, the evidence is inconclusive.

The one undoubted tactical success of the World Cup campaign was the use of Arjen Robben as a roving second striker alongside Van Persie, making the fullest use of his pace on the break. Van Gaal seems initially to have regarded Ángel Di María as being in a similar mould – not as technically gifted as Robben, perhaps, but quick, dynamic, direct and full of energy. However, that ploy has failed, in part because Di María seems to have lost all confidence since his house was burgled and in part because for him to operate like that relies on the opposition attacking United, and the vast majority of sides in the Premier League tend to sit deep against them.

In a sense, the Dutch struggle has been replicated at United: against better teams, the counterattacking ploy has worked passably well; against those who set up to defend against United, it has led often to a string of long balls being lofted at Marouane Fellaini.

The long-ball issue is a fraught one and one that is perhaps more complex than is often allowed: English football, remembering the excesses of Wimbledon, Watford and Cambridge, regards the whole notion of long balls as toxic. Yet direct play is key to the rapid transitions that have always characterised total football. Of teams in the top five leagues in Europe this season, only Wolfsburg have played more accurate long balls than United; next on the list is Bayern. At their most unimaginative – as in the final 25 minutes against Arsenal on Monday – United are guilty of overusing that long diagonal aimed at Fellaini but at the same time the rapid transfer of the ball from front to back has always been a key component of Van Gaal’s philosophy.

Highest average number of accurate long balls per game of the biggest five league in Europe

Similarly, the statistic that United have passed the ball back to their goalkeeper more often than any other Premier League side this season has been latched upon and, in some quarters, heralded as evidence of an irredeemable defensiveness. But Van Gaal has always demanded his goalkeeper be regarded as the 11th outfield player: Edwin van der Sar, who played for Van Gaal at Ajax, was supremely confident with his feet, while part of his legacy at Bayern is the freedom with which Manuel Neuer plays.

Other aspects of the philosophy are less obvious. When Van Gaal speaks of his philosophy, is he talking of the idealism of the 90s or of his more recent pragmatism? Often this season United have seemed overcautious, waiting for the opportunity to counterattack against teams that have little intention of attacking them, and that perhaps hints at a confusion within Van Gaal’s thinking, indicates that prudence, that great curse of maturity, has edged out the boldness of his peak years. There is a sense, too, that the anger has gone: Van Gaal this season has been tetchy but never volcanic. Maybe the fire is simply going out. Maybe the genius is getting old.

Of course there are mitigating factors. Although a huge amount of money has been spent, it has not been spent well – and that is probably not Van Gaal’s fault. The presence of two ageing and misfiring strikers has complicated matters. This United squad probably contains only one player capable both of playing at centre-back and operating as the deep-lying playmaker Van Gaal once demanded, and that is Michael Carrick, who is 33 and possibly leaving; and a string of injuries have contributed to the lack of cohesion at the back that presented Arsenal with two goals on Monday.

Van Gaal, almost any manager, deserves the time to try to put this right. Talk of sacking him is short-termist and ignores more fundamental problems at the club and in the structure of the squad in a post-Ferguson world. But that doesn’t change the fact that this season has become a muddle and nor does it eliminate the suspicion that Van Gaal, having begun to tinker with his philosophy, is no longer quite sure what it entails.