And United also set a new record of 11 successive clean sheets, overtaking the tally set by Chelsea during the same season four years ago.
Ferguson said: "The defensive record is a fantastic performance and it is down to the experience we have gathered together in the back four.
"Even though we've had to make changes in the last few weeks because of injuries, they have all applied themselves very well.
"Edwin Van der Sar, who has achieved everything in the game, is as delighted as when he saved that penalty kick in Moscow during the Champions League final.
"He was over the moon in the dressing room and that tells you his desire. He has still got that ambitious streak and wants to win all the time."
Ferguson was also pleased that his star studded attack also delivered goal-power with Cristiano Ronaldo (2), Dimitar Berbatov and Carlos Tevez amongst the scorers as they moved three points clear of Liverpool at the top of the table.
He said: "The form has come good at a good time. March and April are the crucial months but it is good to get our show on the road.
"We saw a ruthless streak that has maybe not been there this season. We hoped it was going to come. We expected it to come become of the standard of forwards we have.
"Tonight was the first indication that it was there. For the first 10 minutes West Brom did very well and gave us a bit of defending to do and we were quite resolute at that stage of the game.
"But once we got the ball in their half of the field, we always looked dangerous."
Ferguson felt Albion defender Paul Robinson was guilty of a reckless challenge on United midfielder Ji-sung Park which resulted in an instant red card from referee Rob Styles.
He said: "I thought it was a reckless challenge from where I was sitting but they tell me from the camera the other side it didn't look as reckless.
"It was a careless challenge when he didn't need to do it. Ji-Sung is on the ground and the boy has come in late, sliding into him and it is careless and reckless a bit."
West Brom manager Tony Mowbray initially refused to discuss the red card but conceded a review of the incident today will decide whether to lodge an appeal.
He said: "That will probably be a club decision really. I am pretty sure our hierarchy will have a look at it and decide what they want to do.
"For me, I will abide by that. It depends what angle you look at it. I don't know what the club will do. They will probably make a decision today (Wednesday).
"It is all about opinion and the referee made the decision tonight. If his angle meant he thought it was a red card, he'll give it.
"If the TV angle show that Robbo didn't leave the ground or show his studs, that it was an honest collision between two players going for the ball, then I am sure there will be a case to appeal it.
"Until we look at it in the cold light of day, we won't know if we are going to make that decision."