Vicente del Bosque's side have lost both of their Group B matches this summer, leaving them out of the competition with one game still remaining.
"My assessment is that the whole world has changed and we haven't kept pace," Marca reports Canizares as saying.
"The players themselves say they weren't good physically and didn't arrive safely mentally. [Changes should have been made] before the World Cup."
Spain conclude their World Cup campaign against Australia on Monday.