You make it sound like the Spurs use some sort of gimmick offense and defense and have been lucky to win. There's a reason the Sun's shoot poorly against the Spurs, its no huge secret, its the same reason every team in the NBA shoots poorly against the Spurs, they play great defense. Duncan is next to impossible to guard one on one, he's too strong, quick, and has pretty good range. Duncan is perfectly capable of playing more minutes, but Popovich is holding his minutes down to keep him somewhat rested for the playoffs. Like a few others in the league, he's basically played basketball nonstop for the last year and half.
You can say all you want about the Spurs not being dominant, or not being a truely great team, but the fact of the matter is over the last 7 years, no team in any sport has a higher winning percentage than the Spurs. Not the Yankees, Lakers, Patriots, Braves, Rams, (insert any team from any sport here). They are a great team, and a dominant team, hopefully they will show you tonight just how great.