From what I've seen I don't think there's much difference in the talent between:
West / Davis
Martin / Crabbe
Ginobli / Henderson
Anderson / Harkless
Even Mills / Roberts
Obviously Kawhi eats Aminu's lunch, and likewise for LMA/Vonleh. Otherwise the talent level of Parker/Dame, Green/CJ, and Plumlee/Duncan isn't THAT huge. Yes, Duncan is the best PF to ever play, but he's been a role player for 3-4 years now - sound fundamentals and mid-range game are the only thing that separate him from Plumlee at this point.