The Blues won 1-0 thanks to Kieran Dewsbury-Hall's strike, with the visitors also playing for the majority game with ten men after Idrissa Gueye's dismissal for clashing with teammate Michael Keane.
Amorim said afterwards: "Forget the result. The result is really bad but I was more concerned by the feeling I had during the game. Everyone should play better today
"The understanding of every situation of the game was not there and then the quality near the box. But most important is the intensity. You can feel it right away, when we start the game. We can feel when we are at the top level in intensity and when we are not, and you cannot win games in this way.
"I am really frustrated by the way we play the game, especially in our home and especially understanding what happened during this week, with the other clubs and looking at the table. Feeling everything in the way we present, especially in the first minute of the game. It is really, really frustrating.
"We need to play the game in a different way. Sometimes, we can do it. Sometimes, we can have a good run of results and performance but then we drop the level and yet we need to win every time."
Amorim admitted Everton were deserved winners on the night.
He added, "If we are not in that place, we are not going to win games and that happened today. They were better than us with 11 players. They defend well and suffer with 10 men. Congratulations to them.
"We cannot change the past. We cannot cry now and think about the last one. We need to prepare, improving a lot of things. The most important thing is to finally understand we need to play every game in high intensity in order to win games."