If you want to narrow your goalposts to base Dirk's "fitness" based on 6 games played in the Finals, hey, go nuts. And his Finals numbers were not bad, hardly "chokeworthy."
So not only are you using a tiny sample, your conclusion is dubious anyway.
Me, I'd look at a player's playoff numbers since the road to a championship requires success at all those levels. He's consistently great in the playoffs and we have a sample of 103 games to judge that.
Your way of looking at things is how we get the silly Spurfan argument "4 for 4 is better than 5 for 7!!!1!!1!!!"