The Circle Rounder was the second in command in a circle, but at the same time, they shared a closer relationship with the circle executives and members than the Circle Master.
In addition, they were more likely to take part in external events than the Circle Master so in a sense they could be considered the face of the circle.
That was why the Circle Rounder was usually the most talented member of the circle.
It was to show a strong face to the other circles.