Los Blancos won 10 consecutive matches after lockdown to claim the trophy, ZIdane's 11th across two spells in charge, before a 2-2 draw at Leganes on Sunday.
"Zidane has finally beaten Messi and he has been a wonderful manager of abundance," Valdano told France Football.
"An abundance of talent and an abundance of numbers, very efficient and well-planned, because it's much more difficult than you think."
And Valdano, who was sporting director at Real when Zidane arrived as a player in 2001, revealed he has been impressed by the Frenchman's growth as a coach.
"It's all thanks to the ever-greater wisdom of this coach without equals, of whom I'm surprised by his evolution in all areas," he said.
"He's a very intelligent and professional man and he uses his experience to improve.
"He won because he was capable, better than anyone, of adapting and adapting his team to the new situation."