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 have 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 . Manchester United players celebrate Chris Smalling 's goal during their 4-2 victory ove Manchester City . Here comes the Belgian . Who is this marauding midfield menace ? Marouane Fellaini was public enemy No 1 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 . Van Gaal is brave enough and bold enough to throw the big man into the action and give him licence to attack , regardless of aesthetics . If his unplayable form continues , expect sales of those daft wigs outside Old Trafford to rocket . Marouane Fellaini celebrates after the influential Belgian gave the Red Devils a 2-1 lead on Sunday . Fellaini leaps to meet Ashley Young 's cross with a header to send Old Trafford into a state of euphoria . Last season , Fellaini struggled to make an impact at Old Trafford and was heavily criticised by fans . Ander-nother one comes good . 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 on board 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 lacked until their spring rising . Van Gaal will no doubt claim similar credit for the resurgence of a reborn Ashley Young . Spanish midfielder Ander Herrera has been in impressive form for Louis van Gaal 's side . The United boss congratulated Herrera after another good performance as United defeated rivals City . Figuring out what 's the Mata . 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 . Juan Mata slots the ball past goalkeeper Joe Hart to give his side a commanding 3-1 lead against City . Mata celebrates in front of the United supporters after firing his side into a two-goal lead . Reputation counts for nothing . 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-emergance of the likes of Mata , Herrera , Fellaini and Young . Radamel Falcao ( right ) has had to settle for a place on the bench after failing to impress Van Gaal . Record £60million signing Angel di Maria has also been made to sit on the bench by the United boss . Stumbling across a system . 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 . Michael Carrick has been key to United 's recent form as his side move up the Premier League table .
Manchester United have won their last six Premier League games . Louis van Gaal has made several changes since 1 last season . Juan Mata , Marouane Fellaini and Ander Herrera have all impressed . Angel di Maria and Radamel Falcao have struggled to make an impact . READ : Van Gaal celebrates derby win with CITY stars from ladies team .