#7 Iker Casillas

The goalkeeper position is the one that has haunted Real Madrid the most in recent years. They have failed to poach David de Gea from Manchester United and the likes of Keylor Navas and Kiko Casilla have done little to ward off their misery between the posts.
At present, it looks like Real Madrid would jump at the chance to reverse their decision of selling Iker Cassilas to Porto. He might be a veteran now, but the World Cup winning captain is still better than the two goalkeepers Los Merengues currently have in their squad.
Iker Casillas joined Porto in 2015 and has nothing much to boast about in contrast to the medals he won at the Bernabeu. However, his sale can't be regretted more often than now, seeing how the club has struggled to find a shot-stopper worthy enough to fill his giant boots at the capital.
Casillas played 16 seasons at Real Madrid and retiring at the club would have been the fitting end to his fairytale career. Had Real kept him, there's no doubt they would have been saved from a seemingly endless headache.