Real Madrid were thumped 5-2 at the Metropolitano yesterday.
Reacting to the result, Valdano said on Movistar +: "Last night (in the Madrid derby) the monster was revived.
"It seemed like things were starting to turn around, but the blow against Atlético forces us to review the current state of Madrid's project.
"The monster of visiting Barcelona or being visited by Barcelona and conceding four goals was revived.
"Atlético ended up dominating Real Madrid in a way we haven't seen in a long time.
"Real Madrid didn't play with the same intensity as Atlético Madrid. In the first minutes, Madrid played with their feet and without much rhythm. And Atlético played in space with a lot of aggression.
"And Atlético clearly won the match up front. Every cross was a real drama for Madrid. And Atlético clearly won the match up front. Every cross was a drama, a real drama for Madrid