The phrase "mere spectator" refers to someone who is solely observing or watching an event without being directly involved or participating. Full definition
Unless City really slip up, things will be quite difficult for the rest of the sides from the Premier League, as they may become mere spectators in Pep Guardiola's title glory, if things don't change at the top of the points» table soon. (beyondtheposts.net)
The Margaret Simpsons and Vida Anims have also phased out and Ghana has now become mere spectators at the Olympics. (ghanapoliticsonline.com)