Ratcliffe singled out several senior players, including Casemiro and Andre Onana, as underperforming and being "overpaid".
Ahead of tomorrow's Europa League clash with Real Sociedad, the United manager said: "Everyone is underperforming. Myself and the players. We can always change that, I include myself in that part of underperforming.
"You are talking about players like Casemiro that have won everything. We know these players can play so much better, that is the focus. He was honest on that. The focus is to change his mind.
"A lot of people will say you are not good enough for the club, but my feeling is you can change that with results.
"In training I feel they want this really bad."
On his squad make-up for the round of 16 second-leg, Amorim continued: "It is too soon for Mason Mount, Leny Yoro is out, Harry Maguire cannot play this one, but I hope to have him for Sunday. Manuel Ugarte is in the squad."
Amorim also commented on news of United building a new stadium.
He added, "It is an amazing stadium. It is in the future, five years from now, so we have to focus on the present. I am focused on winning things at Old Trafford."