If Elena Kagan had gotten the Texas deanship, it is unlikely that she would have become solicitor general. She would not have had the more visible Harvard deanship and the spectacular fundraising record that Harvard enabled.
If Elena Kagan had been chosen for president of Harvard, it is unlikely that she would have taken the solicitor general's job (a step down?), or could properly have left the presidency after so short a time, and that in turn may have kept her off the A list for the Supreme Court.
Yes, this is speculation but there's also a lesson. The lesson is that a setback is just a setback and, although you can't know it at the time, may actually position you for a bigger leap forward later.
Or: Sweet are the uses of adversity (quoting WS).