However much you admire Michael Carrick commanding the area in front of the back four or how Ander Herrera knits everything together, the eye cannot help but be drawn to the frizzy halo clanking about in midfield

Throughout his career as a coach, Louis van Gaal has been dogmatic, but perhaps the only thing he is dogmatic about is the fact that he is right. He came to the Premier League and, because he’s smarter than anybody else, he took the one surviving facet of the traditional English game, and showed how we could have been using it far more effectively all these years. Look, he said, I like this target man of yours, but why on earth haven’t you been using him in midfield?

The great fascination of Van Gaal in the decade since he took over AZ Alkmaar has been his willingness to evolve, to adopt new formations and to find new ways of doing things. He had revised the typical Dutch way of playing at Ajax and Barcelona. He had fiddled with a 4-2-3-1 with the Dutch national side but it was when he was presented with a squad of lesser players that he was forced to improvise, and found glory in a counterattacking system. Now he has a new conceit: Van Gaal may speak of Juan Mata as a “false right-winger”, but redeploying a central creator to drift in from the flank has been done before; his great innovation – his great joke, almost – has been the use of Marouane Fellaini as a deep-lying target man.

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Since his time in Alkmaar, Van Gaal has constantly changed approach. Whether it is the pragmatism of experience or whether he would have been less tied to the classic Dutch model – which he had reinvented anyway – had he been at clubs other than Ajax and Barcelona is impossible to be sure, but what has been in evidence since he got to United has been a mind that is constantly analysing, constantly playing with new possibilities. Perhaps that did lead to the constant chopping and changing of formations early in the season that unsettled some players, but if the performances against Tottenham and Liverpool are indicative of what is to come next season, few will be too concerned.

At Bayern, Van Gaal endured a miserable start before everything, quite abruptly, clicked in a 4-1 away win over Juventus. It has taken longer at United, but perhaps what happened against Tottenham was the same process, the moment when the dots suddenly coalesce and the picture becomes clear. It is, perhaps, a little early to be saying with any certainty that the philosophy is instilled – and certainly there were reasons for concern in the second half at Anfield – but the authoritative nature of that first-half performance away at Liverpool suggested a radical change of mood.

But however you look at it, however much you admire the pace of some of the passing or how Michael Carrick commands from in front of the back four or how Ander Herrera knits everything together, the eye cannot help but be drawn to the frizzy halo clanking about in midfield. If Fellaini looks out of place – as though the real footballer has escaped and his fellow POWs are trying to con the guards that he’s still in the line at roll-call with a model constructed entirely from the contents of the broom cupboard – it’s because he is out of place, and that is what makes him devastating.

There is nothing particularly extraordinary about the shape United have used in recent weeks. It’s a 4-3-3, a basic 4-3-3 in which the right-sided forward drifts inside, creating space for an overlapping right-back. The central triangle of midfielders is lopsided: Carrick at the back, sitting just in front of the two centre-backs; Herrera advanced of him to the right, linking Mata and Antonio Valencia; and Fellaini further advanced to the left, always looking to push forward to play almost as a second striker – a role that, in fairness to David Moyes, it should be acknowledged that he often played at Everton.

There have been times this season when United have been a little over-reliant on the long diagonal aimed at Fellaini but as an option he can be devastating. Poor Emre Can, an elegant passer of a central defender who has prospered this season because he has had Martin Skrtel to do his heading for him, found himself in direct opposition at Anfield and was battered from the first minute.

According to stats from whoscored.com, Fellaini has been involved in nine aerial duels per 90 minutes played this season, winning 5.5 of them. Only four players – Ashley Barnes, Graziano Pellè, Peter Crouch and Christian Benteke – have been involved in more per 90 minutes.

Barnes has, at times, played in midfield this season but Fellaini’s nearest challenger of those who play regularly in midfield is Mile Jedinak, who has been in 4.7 aerial duels per 90 minutes – and the majority of those in a defensive context. Fellaini, in other words, contests almost twice as many aerial balls as any other midfielder.

Facebook Twitter Pinterest Marouane Fellaini, centre, contests almost twice as many aerial balls as any other midfielder. Photograph: Jan Kruger/Getty Images

But it’s not just that he is good in the air, knocking the ball down for team-mates in a blur of elbows. English football has been used to that almost since it accepted in the mid-1870s that passing, as opposed to head-down charging, might not be entirely unmanly. What makes Fellaini – or at least Van Gaal’s use of him – special is that he is winning those headers with runs from deep. Others have had success using target men wide – Ian Ormondroyd at Aston Villa under Graham Taylor, Emile Heskey at Liverpool under Gérard Houllier and with England under Sven-Goran Eriksson, Jostein Flo with Norway under Egil Olsen – attacking the back post, but using him as a central midfielder is new.

A deep-lying target man is never going to offer the outlet for a defensive clearance a frontrunner can – he’s not going to hold the ball up with his back to goal and lay the ball off – but coming from deep can offer advantages. As Fellaini attacks one of those long diagonal balls hit by Valencia, he will usually have a run of 10, perhaps 20 yards. That means he’s moving at pace, while a defender may be jumping from a standing start: the momentum is with Fellaini.

The importance of acceleration room for dribblers – the advantage if they are moving at speed when they meet a challenge – has long been acknowledged (and is one of the reasons for the widespread adoption of the back four in the early sixties); the use of Fellaini shows the importance for headers as well. A midfielder could be deployed against him, but how many other midfielders have Fellaini’s size or power?

Fellaini is big and awkward and comes from a position in which he can punch holes in opposing rearguards. It may not be subtle, it may not be the style that stereotype would demand from a master Dutch strategist, but it is working. Van Gaal has found something else to be right about.