Yeah, that's an unranked player, someone that's very new and that has not reached Bronze yet.

Depends on your definition of casual, but it's not someone who queued "Casual game" and ended up in a Ranked match lol.

I'm not sure I agree that Unranked players should be in the same games as Gold players.

I prefer the old matchmaking system :

Unranked-Bronze-Silver could play together
Silver and Gold could play together, but Gold couldn't play with Bronze or Unranked

Having Gold with Unranked players in the same match seems a bit much...