Sohail Abbas & Taeke Takema.
In the past the ideal place to flick the ball from a short corner was to the top, left or right of the keeper. This was due to the fact that the goalkeepers were taught to take 2 steps off their line and log (lie down, stretched horizontally on the ground) with line stoppers left and right of him, to prevent the straight, low strike.
Hence over the past few years Darwin's theory of natural selection, where only the fittest survive, has forced the keepers to stay more mobile at short corners. Nowadays keepers will avoid compromising their agility and try and stay on their feet as long as possible. This in turn has forced the corner specialists to adapt their action. You will see a much more varied placement of the drag flick these days to keep the netminders off balance. However the more successful trend seems to be edging towards a low drag flick to the right of the keeper (left from the strikers point of view) where the line stop will be slightly more focused on a flick aimed at his head.
At the end of the day the perfect drag flick is a drag flick that keeps the goalkeeper guessing as to where it's going, top, bottom, left, right.
Variation is the spice of life.