While Duncan plays at a much higher level than you would expect he's is no longer a superstar. Parker and Ginobili are both a step to several steps slower. IMO Leonard is closer to being a superstar at this stage than Duncan, Parker, or Ginobili.
Dude, Leonard had two really good games in the series, but he isn't better than Parker/Ginobili/Duncan. Please look past the last 4 days.
Like I said, Duncan is no longer a super-star athletically, but he still brings the super-star mindest, IQ, and intangibles that only a player who has been arguably the best player at his position for more than a decade can bring.