The 25-year-old has defended the Liga champions' decision to sell him and the current Chelsea winger, as he has made it clear only the very best succeed at los Blancos right away
Jose Mourinho has received plenty of criticism in recent weeks for his alleged reluctance to use youth players, but Granero has insisted that only the very best succeed at los Blancos right away, and players sometimes need a spell elsewhere to make the final step up.
"Of course Real Madrid would love to have many players in their first team from the academy," Granero told Revista.
"You have to be one of the greatest players in the world to play in the first team, though, and sometimes there is a player who is able to do it and sometimes there's not.
"The important thing is how Real Madrid has helped all their players who now are in the first team, like Iker Casillas, Alvaro Arbeloa - there are many - and how Real Madrid has helped the players who now are not in the first team like me and Mata. This is not the failure of Real Madrid.
"If you are not good enough, you have to try and find your way abroad. If you can find your place in the first team and you are good enough, great.
"Real Madrid are the greatest team in the world and playing for them - especially for the people in the academy - cannot be easy. If it was easy the team wouldn't be that big and that good."
Granero left Madrid for Loftus Road on a permanent basis in the summer transfer window, while Mata said farewell to the Santiago Bernabeu side in 2007 when he joined Valencia before departing for Stamford Bridge last summer.