From what I've read, O'Bryant came late to organized basketball, and thought himself fortunate to get a college scholarship. When he went to college, he knew he needed a lot of development, and figured he'd be red-shirted (he wasn't). He then did better than expected in competition, and at the end of his sophomore season had a nice tournament showing. So even though he was clearly a project, he jumped at the chance to get pro money (and wouldn't we all).
Therefore, if indeed he was repeatedly dominated by inferior college centers, then I'm not that surprised. I can think of a long list of NBA big men who took quite a while to grow into their bodies and to develop their games. (And an equally long list of guys who never did.)
One of the great things about sports is having the chance to watch that process. Let's see what happens with the kid.