Rooney to United's 3-0 defeat at Manchester City on Sunday.
"I want to be as supportive and positive as I can be on the manager and the players," Rooney said on his personal podcast.
"But it is very difficult to sit here and say we are seeing progression, and at least we're seeing things that will get results in the near future.
"We're seeing none of that, and it is very difficult. There was an image towards the end of the game where I saw the Manchester United fans leaving.
"You could hear the fans singing Amorim's name, but I think that is so powerful that the United fans were leaving the game.
"You know the game is over and I think they were very disappointed in what they were seeing. It is hard to see how it continues.
"What are the patterns? What are we seeing what might improve the team moving forward?"
Rooney added, "I think after the last year when (Erik) Ten Hag got sacked and Ruben came in, we're hearing how they're going to play and it is going to change.
"I think if the manager is honest with himself, it has got worse."