And yet....
Parker won Finals MVP last year.
We have a great TEAM. I'm not sure any player is "replaceable."
Name a le, and I'll name you a "role-player" who is responsible for at least one crucial win.
(some examples)
2003: Steve Kerr against Dallas.
2005: Horry, game 5, against Pistons.
Now, does that make Kerr and Horry equal to Tim Duncan?!? No, of course not.
But I doubt we'd have won those les without them.
To state the obvious: Teams win Championships. See 2004 Pistons over "dream-team" Lakers for evidence of that (keeping in mind, of course, Malone was hurt).
If the Spurs beat the Lakers, it's not because Manu > Tim (or vice-versa). It's because as a TEAM, Spurs > Lakers.
EDIT: Just to add, in case anybody sees this as a slam on Duncan, I think Tim's leadership is a big part of why the Spurs have a winning Team. Oh, and he's the best current big man in the NBA. That doesn't hurt.