Parker hasn't a lot of talent to pass the ball.He is not able to make good one handed passes with the left hand.He doesn't have a great vision of the court.Manu makes 2 games with more than 10 assist when TP was out and he never was PG but he has more ability with the ball on his hands.
The key of TP is his speed and quickness.
The player who has to make the difference is TD like always.Without him we will be a lottery team.When Duncan retires we will not make the playoffs if TP has to be the leader of the team.He's not one of the top10 NBA players,even he's not one of the top20.
Right now if he has to be the leader then easily he could be one of the worst franchise player of the NBA except teams like Charlotte,New York or Indiana