Ramos scored as Madrid lifted the Champions League title last weekend in Lisbon, and Sanchis believes that the Spaniard's consistent performances in the heart of the team's defence could see him recognised with the top individual award in the game.
"We've known for a long time that Ramos is the best defender in the world, I've never doubted that," Sanchis told members of the media.
"I already put him amongst the candidates for the Ballon d'Or. A player of his quality and performance has to be considered.
"I have a theory that teams are built from back to front. The centre of defence is crucial because you have the ability to dictate and Sergio influences because his game is not only defence. He's a complete player."
Ramos has also been praised by Real president Florentino Perez, who called him a "phenomenon" on Wednesday.