Tragic Poet Mosaic

View of the "Tragic Poet" mosaic because of which scholars have called this house "The House of the Tragic Poet."  It appears that a group of male actors are gathered around a seated older male and are putting on masks and costumes for a performance.  Note from right to left the figure getting into a garments, assisted by a boy, the flute player, and the two figures on the left clad only in brief garments—one with a mask on.

The seated figure seems to be selecting a mask from those found in a basket at his feet.  Could it be that the seated person is the poet who wrote a play that the actors are about to perform?

Why this is in the center of the tablinum seems to be a mystery.