The Dutch goalkeeper set a new British league record after a 13th consecutive clean sheet in the 1-0 win over the Hammers on Sunday.
Ryan Giggs scored the only goal of the match.
Fergie told Sky Sports: “The clean sheets have been a topic, but it doesn’t just change the emphasis on our game.
“I think today we’ve had some fantastic possession of the ball and the players we’ve got on the pitch are attackers – Cristiano, Dimitar, Carlos, Ryan and Paul Scholes, and Michael Carrick.
“What the back four have done is really focus and concentrate on their job. They’ve got pace and are quick and, of course, to have a goalkeeper like Edwin van der Sar is just fantastic.”
He continued: “We felt today, knowing that West Ham is always a difficult ground for us, that we should have the most experience we can.
“Ryan and Paul Scholes have been here so many times and they know exactly what is needed here.
“Michael Carrick, Carlos Tevez and Rio Ferdinand are former players here and that also helps actually to handle the atmosphere.
“It was a fantastic atmosphere and they really get behind their team, and we’ve beaten a very good team today.”