The red folk and the purple people were distinctive in their hue.  In contrast, the Set Up bunch were chameleon, and to the casual observer they could pass for members of the congregation. That was by design, to be known only by their levite nature, their early arrival and late departure and (if you looked closely) by their hands.
The early bunch had remarkable hands. They were strikingly ready and willing, and could be turned to a wide variety of tasks.
They could never be described as specialist, and would never wish to be.  Their true specialty, if they have one, is only to be quick to serve and never draw attention to themselves.  
If they were ever persuaded to wear team tee shirts, they would have 'Ninja' brazoned across the back.  And that would be kinda cool.