United responded to a poor first season after Ferguson's retirement by bringing in Van Gaal and underneath him the likes of Daley Blind, Angel di Maria, Radamel Falcao, Ander Herrera, Marcus Rojo and Luke Shaw.
The new signings have helped United into the top four already despite some indifferent performances, and Ferguson believes fresh faces were needed.
Referring to the £59million capture of Di Maria from Real Madrid, he told MUTV: "When you can identify ability like that for Manchester United, they have the resources to do that - fees I never quite equalled but they needed a big injection this year."
On the other signings, he added: "Herrera played against us three years ago for Bilbao, he's a talented young player and we scouted him quite a lot. He's quite aggressive for a lad who's not got a great frame.
"I watched Rojo at the World Cup and thought he did well. He's capable of playing left side or centre back.
"Luke Shaw we tried to get when he was 16. They (Southampton) wouldn't sell him but they always said we'd be the first to know if he did. He's a talented boy, good footballer and likes to get forward.
"Daley Blind is a common-sense footballer, a version of Darren Fletcher a few years ago
And Falcao is the one we're all waiting to see, he's got fantastic goalscoring ability."
Despite the big-money arrivals, Ferguson is pleased that Van Gaal has decided to use the club's academy as well.
He added: "The rebuilding of the team, they've brought in some good quality which is really important because you need quality at Manchester United, you need the best players.
"What's pleased me about Louis is he's given about seven of the young kids their debuts, which falls into line with the history of the club
I think the supporters will respond well when a young player gets his opportunity."
Ferguson was often pictured in the stands last season as the man he initially chose to replace him, David Moyes, struggled to get the team performing.
There was never anything to suggest Ferguson was influencing Moyes, but he is adamant he has nothing to do with Van Gaal when it comes to first-team affairs.
"There's no ongoing dialogue. He comes into my office sometimes after a game, we have a chat, it's not a matter of picking up the phone to him as he's a very capable person, a strong leader
He knows what I'm about but there's no need for him to phone me," he said.
Ferguson remains a United ambassador and director, as well as filling a number of other roles
He continues to work with UEFA and the League Managers' Association, but says fewer managers are now calling him for advice, as was often the way in the past.
"One or two do, not many. I think they probably think I'm dead!" he said.
Source: PA