I can understand the PhD part: the programming involves a different mindset than bio and chem: "It's more of a craft, than an art" -- a neurobio PhD. To paraphrase, it is more dependent on wisdom than cleverness.

The math tidbit is interesting though. What other examples have you seen of good mathematicians being lopsidedly talented in one area? What kinds of areas were these? I can somehow see real analysis involving a different ability than that of discrete math.