Jose Mourinho criticized some of the recent transfer dealings of Manchester United before his arrival.
"Manchester United sold players that I would never sell and bought players that I would never buy," Mourinho said.
"I would never have sold (Angel) Di Maria, Chicharito, Danny Welbeck -- never, no chance."
Di Maria was sold by United to Paris Saint-Germain in 2015 after one season with United. Hernandez joined Bayer Leverkusen in a cut-price deal later that month.
Asked if Manchester United were capable of returning to glory days past, Mourinho said: "Forget it. Don't try to go 10, 20 years ago because it is not possible any more.
"We are not ready to be Manchester United. We are not ready to be a dominant force. We are not ready to try and win everything."