Ferdinand says that despite his tough start to life at United, he is confident that Van Gaal will be a success at the club.
He told BBC Sport: "In pre-season, I was really excited for Man United. They looked really fit and decisive and they had a good understanding of the system.
"It was almost like a complete reversal when the season started. I think they'll get it right. I think the manager who's there now gets things right.
"I have every confidence he'll bring back good times at Man United, it's just a matter of how long."
QPR face United in their Premier League clash on Sunday.