United have flattered to deceive during Van Gaal's reign, and he is widely expected to leave Old Trafford at the end of the season.
Nani has lifted the lid on the former Barcelona and Bayern Munich boss' managerial style, while also comparing United's current squad unfavourably to those assembled by Alex Ferguson - the man who signed him from Sporting in 2007.
"He didn't use me a lot in pre-season. I was the player who had the least time in all the games and I was feeling, 'This coach doesn't count on me'," Nani told the Sunday Times.
"He and his assistant were shouting at players like we were kids, like 18-year-olds.
"And I think, 'This is not the way to treat us because I am professional, I am training every day, I'm doing nothing wrong, I'm putting quality in the training'.
"Now when you see Manchester, it's not Manchester. With all respect to the players who are there, the personality, the mentality is all different.
"When you see Manchester United go inside the pitch you see a new era.
"Before you had big names, experienced players who represent so many years at the club. Now you see players who are maybe in their first year, their first time in the Premier League. It's all new."
