Amorim has been pilloried by the likes of Gary Lineker, Gary Neville and Ian Wright.
But Dalot told Rio Presents: “Ruben is someone who is really important to this club’s history.
“It’s bold to say and people might not believe it. But as soon as he came, he changed a lot of things that people don’t see.
“He is a guy that has to be in a disciplined place. The standards have to be high. He tried to do that straight away and we had to adapt to his way of thinking very quickly.”
Dalot, 26, added: “What we did on the pitch did not work in terms of results.
“But Ruben created a great group of players that we have now. If you see our squad, our new signings have elevated us."
“It is always sad when these things happen because ultimately you are judged by results.
“He tried really hard to implement discipline and standards as soon as he arrived.
“But in the Premier League you do not have much time to prove that you are good enough. But unfortunately we couldn’t win.”