Random chance doesn't have more validity than skill, which is one reason why South Africa was outscored 38-12 in three games. But between two teams close in skill level, where one might win 45 percent of the time, the other 55 percent of the time, in six games that could just as easily be 4-2, 3-3 or 2-4.
As for the Bill James quote, he's right that it's an oversimplification to claim that leadership, chemistry, etc. have nothing to do with performance. But it's also an oversimplification to claim that everything can be explained by those things. Sometimes one team beats another team regardless of their relative skill levels, chemistry, leadership, make-up, what have you.
None of that makes a hill of beans, because what counts is who wins. All four teams in the finals are extremely talented. It's not as they're not qualified to be there. But I don't think the reason they're there is solely explainable by the claim that they were better put together as teams, they had better chemistry, leadership, etc.