Van Gaal's appointment was greeted with great fanfare at Old Trafford this summer, and a near-perfect pre-season tour raised hopes of a tilt at the title.
But after 10 matches United are 10th in the Barclays Premier League having gained just 13 points.
The fact that David Moyes, who was eventually sacked after just 10 months in charge, had four more points at this stage last year shows just how poor United have been in the first quarter of the season.
''It's not good enough,'' the United boss said.
'I feel, myself, very lousy for the fans firstly, but also for the board because they have a great belief in me and my players and my staff and when you have 13 points out of 10 matches you are not doing well.''
Unlike Moyes, Van Gaal had a favourable run of fixtures at the start of the campaign, b ut only took a point from the games against Sunderland, West Brom and Burnley
Last week's derby defeat to Manchester City, as well as losses against Swansea, Leicester and MK Dons have also been hard to stomach for the Dutchman.
The pressure on Van Gaal is compounded by the fact he spent over £150million on six new players in the summer.
But Van Gaal, not for the first time this season, demanded patience from the supporters in his press conference the day before United host Crystal Palace.
He thinks his philosophy will make United a better team in the long run.
"Yes, that is what I am doing," said Van Gaal, who has previously enjoyed success with Barcelona, Bayern Munich and Ajax.
"I am training in another way than most of the other managers are doing
I train them in their brains
Every player has to know why they are doing things on the pitch."
In fact, the former Holland coach says it may even take three years to rebuild a club whose name is synonymous with success.
''We are in a process and that process shall take more than one year,'' he said
''It shall take three years
"I cannot say when the results are coming
When I did it with Bayern Munich it was December 8
It can be February 1
But it doesn't matter
This is a process of three years
I have signed for three years.
"Our goal (this season) is to get back in the Champions League."
Van Gaal struck the table in front of him on one occasion during a tense press conference at the club's training ground in Carrington.
His mood has been soured by the news that he will be without any fit senior centre-halves for Saturday's game at Old Trafford.
Jonny Evans, Phil Jones and Marcos Rojo, who is out for up to 12 weeks with a dislocated shoulder, are all unavailable, while Chris Smalling is suspended following his silly dismissal against City.
When asked whether he would enter the transfer market for a defender in January, Van Gaal, who has been linked with Aston Villa's centre-back Ron Vlaar, said: ''It is clear that a lot of things happen and you can judge better in good times than you can in bad times.
''Maybe you are right (about buying in January) but we have to see that.''
Van Gaal also has injury problems up front.
Radamel Falcao has missed the last two games after receiving a kick to the calf in training and he looks set to miss the Palace game on Saturday too, much to his manager's dismay.
Van Gaal was unable to say when the Colombian will be back.
"That is always dependent on the progress on his injury," he said.
When asked whether Falcao's injury was serious, Van Gaal replied with a blunt: "No."
Meanwhile, Palace boss Neil Warnock feels Wayne Rooney will play a major role in turning Manchester United back into a title-winning force.
The Crystal Palace boss takes his side to face Rooney's Red Devils looking to arrest an alarming slide in form.
The Eagles have taken just one point from their previous four Barclays Premier League games and slumped to a 3-1 home defeat to Sunderland on Monday night.
A trip to United may not be as daunting as in previous years but, with Rooney likely to be pulling the strings, Warnock believes the 29-year-old skipper remains a key figure at the club.
"I think he's been a mainstay in Man United and he will be instrumental in them getting right back to the top in the next two or three years," Warnock said of the England captain - who is set to win his 100th cap next week.
"I know he's on a lot of money and so he's open to criticism but, just the way he is, the fans love him and he comes back in and plays in midfield and he'll pop out wide and up front and he just wants to play.
Despite being named as United's captain after the departure of Nemanja Vidic, Rooney's place in the United side is arguably more under threat than ever with the signings of Angel Di Maria and Radamel Falcao adding to the likes of Robin van Persie, Juan Mata and Adnan Januzaj - as well as Rooney
The British transfer record was broken to bring in Di Maria from Real Madrid but Warnock refused to criticise United for throwing money at the squad as they look to become title contenders once again.
"To be fair it's not my business," he said
"If they've got the money, spend it
I don't blame him for spending it, I wish I could have bought Di Maria, I think he's one hell of a player
"That's the kind of club they are, they're looking for those players and world-class players and that's why they'll always come back up."
Source : PA
Source: PA