Man Utd's record buy Angel di Maria has not started since FA Cup defeat to Arsenal - and Van Gaal's men have won all four games.
Paul Scholes believes Angel di Maria's red card against Arsenal was the turning point in Manchester United's season.
Di Maria received two bookings for diving and tugging referee Michael Oliver's shirt in United's FA Cup quarter-final defeat to the holders last month.
The result all but confirmed a second trophyless campaign for United, and with Luke Shaw also sidelined, Louis van Gaal was forced to alter his starting line-up.
United have since won their last four games, scoring 12 goals, to extend their winning run in the Premier League to six.
Club record signing Di Maria has not managed to regain his place in the starting line-up since the Arsenal defeat and Scholes is impressed by Van Gaal's reliance on an attack-minded midfield
"I still feel that Angel Di Maria’s red card against Arsenal was critical in allowing Van Gaal to build this new-look team," Scholes said in his Independent column.
"Looking at the side it seems to me to be a triumph of the underdog - Juan Mata, Marouane Fellaini, Ashley Young. All of whom looked like they could be out the picture at the start of the season and are now having a big impact.
"The formation is bold. It is much more attacking and more what I expected of Van Gaal when he arrived.
"There is a spine of four players – Michael Carrick, Ander Herrera, Fellaini and Wayne Rooney – that runs through the middle. Then Young and Mata wide."
Scholes insists Mata, who has scored three in his last three, has brought 'composure' to the United side.
And the United legend also revealed Ryan Giggs decided Marouane Fellaini's best position was as an unorthodox No.10 during his four-game caretaker stint in charge.
Along with Nicky Butt and Phil Neville, Scholes assisted Giggs at the end of last season and has disclosed why they decided to play Fellaini further forward.
"When I was coaching under Ryan Giggs at the end of last season, we always felt that Fellaini’s best position was as an unorthodox No 10 – the role he is playing now," Scholes added.
Image Source: Getty Images.
Referee Mike Dean shows Paul Scholes a red card after his high footed challenge Pablo Zabaleta of Manchester City during the FA Cup sponsored by E.ON semi final match between Manchester City and Manchester United at Wembley Stadium on April 16, 2011 in London, England.
"When he first joined United, David Moyes had played him as a central midfielder but I don’t think controlling the game from there is Fellaini’s biggest strength.
"When I played against him when he was at Everton, he was just a giant nuisance: elbows up, big and strong and always liable to peel off and take up a position at the back post. That is how Van Gaal is playing him now and not asking Fellaini to do the things he finds more difficult.
"I do wonder whether Fellaini has the quality to win games in the Champions League latter stages but that is for another day. I always found him a good, committed player who trained hard."