Amorim spoke to reporters after his team lost 3-1 to Brighton in the Premier League at home.
The loss, the third in a row they have lost to Brighton at home in three league seasons, led to Amorim telling the media that this was the worst United team in the club’s history.
Speaking on Sky Sports’ Monday Night Football, Carragher said: "I don't know Man Utd's history as well as Gary Neville but I must say it was one of the most bizarre and ridiculous things I've ever heard a manager say.
"Why you would make a comment like that… that's the type of comment a pundit would make, someone in my position, and you'd have to defend that. I don't know what he gains from that, what the benefit is.
"We all know it's a poor Man Utd team. They'd lost another game at home to Brighton, they'd done that in the last couple of years anyway. We know it's a tough season, we know it's a poor team. He has just loosened it up. That will be a quote that follows him for the rest of the season.
"He said to the journalists there, 'I'll give you your headline'. Why you would like to do that as a manager, I'll never know."