Dirk is a 10 on offense while Duncan -might- be a 9 (though with the double teams he draws you could consider him a 10). Meanwhile, Duncan is a 10 on defense while Dirk MIGHT be a 7, but is probably hovering around the 6.5 range.
Calling Dirk a more complete PF than Duncan is in the same vein of thought that likens Kobe Bryant to Michael Jordan. Defense gets zero respect in today's league because it isn't flashy. Kobe is flashy on offense, perhaps as much so as Jordan was, so let's summarily dismiss MJ's contributions on the other side of the court.
Dirk is a pretty flashy player. Duncan is not. That's the difference, and that's what bothers people so much when the Spurs win les, because they don't let the other team make spectacular plays. They shut down the opposition, and in doing so people think it's a poorly played contest, when in reality it's a defensive mastery. They scrum, make tough plays in the post (something I've rarely seen Dirk attempt). And so it is with Duncan. There is not a single player in the league right now that would make a PG think twice about driving into the lane besides Shaq, and with the speed he moves at these days, Duncan is the best post defender in the game.
Say all you want about Dirk's slashing, his great jump shot, his "improving" defense. If you even try to offer a single reason why Dirk is a more complete player than Duncan, you haven't been around the sport long. The article by Simmons is ridiculous. That's like calling Nash the "most complete" point guard in the history of the league. Sure, some people will buy it because Nash is hot right now, and he makes incredibly flashy plays. He looks unstoppable, until any top 10 PG comes along and makes him and the entire Suns team look absolutely lost on defense. Fans who saw Magic rise to prominence just smile and nod and say, yep, Nash is a pretty good little point guard.
Dirk is a pretty good power forward.
It's funny though, because those two "complete" players have 0 Finals MVPs and 0 les between them. Yet they're supposed to be the best at each position? I guess it's not surprising. Young fans equate Sportscenter highlights to quality basketball. Older fans are a bit more cogniscient of the fact that Defense never gets credit yet always takes the le home.
Knew something was off about that statement, so I fixed it for you.