Depends on commentator(s). If they don't mention someone, then he's more likely to be invisible; he can be part of he same group or attack as others yet if commentators don't pick him out and do pick others... Then it depends heavily on who you do do follow or do not. Then it depends on whether one has some problem, i.e. being caught back on the wind or crashing or sometinh.
For me Kreuziger surely was not ninja, he was part of at least two attacks and he was puling front quite a lot there so he was pretty visible, then was was falling back or being overrun by favourites. And he was only one of his team in any group, so pretty easily distinguishable. Quite surprisingly he has quite a lot of air time on TV. Then again, I realize that's my point of view.
Someone is argumeting by Aru dangling metres from the leaders group - well with Kreuziger that was similar.
So more or less this is pointless question because it mostly depends on the spectator.