People have gotten angry at Barkley's comments, and him predicting that "the Spurs will not survive this first round series" may indeed be hyperbole. However, the one thing he is absolutely correct on is that the Spurs frontline IS smallish. There's no getting around that.
We all know Pop isn't going to play Splitter, which further underscores how smallish that frontline rotation really is around Duncan. So all they really have is Duncan and 2 6'9" PFs, (one of which is red-haired, finesse, stetch-4), and an undersized 6'7" center. It's just not enough.