Manchester United’s thumping 4-2 derby victory over City is the latest vindication for the methods of manager Louis van Gaal.

The Dutchman spent long periods of the season under fire for the disjointed performances of his misfiring team but is now basking in the glory of a dramatic upturn in fortunes.

Convincing victories over Tottenham Hotspur, Liverpool and City now has fans believing in Van Gaal’s fabled philosophy.

With a place in the top four all-but-assured and local bragging rights restored, here are five things the manager changed to transform United.

Marouane Fellaini was public enemy number one last season, appearing to epitomise everything that was wrong with United under David Moyes. The scapegoat with the funny hair found it no laughing matter and this season has thrived under a manager who is utilising his strengths.

Louis van Gaal is brave enough and bold enough to throw the big man into the action and give him license to attack, regardless of aesthetics. If his unplayable form continues, expect sales of those daft wigs outside Old Trafford to rocket.

Some United fans will tell you that they always knew Ander Herrera would do the business, he just needed the opportunity. Van Gaal however, will say that the box-to-box Basque boy is now thriving because he has taken onboard his advice.

The manager bemoaned a lack of composure from Herrera which saw him start just one Premier League match from October to mid-February.

Since his return he has provided a cutting edge that United have lacked until their Spring rising. Van Gaal will no doubt claim similar credit for the resurgence of a reborn Ashley Young.

Juan Mata failed to live up to big expectations last season and looked like another who would prove to be a big money flop. In fairness, it was a tall order to perform in a sinking side and some wondered if, given an apparent lack of pace, he would ever fit in.

The man who arrived in a helicopter, however, finally has lift-off. Surrounded by willing runners he is now a key cog in a well-oiled machine. Loved by Chelsea fans, he is now close to being adored in Manchester. The Special Juan.

Van Gaal has been dropping hints about his philosophy all season. The message came loud and clear when he was asked why he had preferred unproven teenager James Wilson to £280,000-a-week loan man Radamel Falcao.

‘If a player cost £95m or £5,000 it’s not any different for me,’ Van Gaal told us. ‘You have to prove yourself.’

It is that mantra that has seen the likes of Falcao, £60m Angel di Maria and old pal Robin van Persie spend large parts of the season checking their backsides for splinters and has paved the way for the re-emergence of the likes of Mata, Herrera, Fellaini and Young.

Despite snatching unlikely victories, United had laboured for long chunks of the campaign with the atmosphere at Old Trafford often flatter than a (Dutch) pancake.

Not now. The three at the back is long gone and while it might not be the 4-4-2 the frustrated fans chanted for at QPR the 4-1-4-1 (with a special mention for Michael Carrick) some would say the boss was forced into thanks to injury is not far off. By luck or design it is working.

The Theatre of Dreams is rocking again and the nightmare of last season seems a million miles away.

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