There is no fact of the matter to that. The numbers do not lie -- you crossed halfcourt looking to score against us in '03 and your chance of doing so was LESS than against any other team in the NBA that season. Perhaps it was just a down year and there were no lockdown teams? Unlikely, given that the numbers stack up equally as well as teams we want to call lockdown today.
But even a great defensive team can be tempted into not being great. The mighty Spurs this season experienced EXACTLY the same thing in their series against Phoenix as we did three years ago against Dallas. Its their defense's Achilles' heel, just as it was ours -- they like to run now. So Phoenix ran, the Spurs ran, and end result is the Spurs, the SPURS, give up an average of 104.0ppg and allow their opponents in a WCF to shoot nearly 50% as a team for the series (.496), which is pretty much unheard of. It happens. And if Duncan had blown out his knee in the second game of that series I suspose we would all be sitting around here talking about how the Spurs collapsed defensively and really weren't an elite defensive team? Nope.
P.S. And no, the numbers did NOT say that Dallas was an elite defensive team this year. Not at the level we once were. They did however say they had become a good one, and that is for the most part true, albeit still shaky and not there every night for them. More like where we were in '01 when we first started to emerge as a good defensive team.