The lesson in particular is that whenever humans are involved they will not always act as you predict. Players who are better on paper (and Madden) will suddenly disappear on the field. The coach will call a play asking a slow running back to try and run a sweep designed for a faster player.
The quarterback will get nerves and panic and forget what color his jersey is.
What does this have to do with identity management and of course virtual directories?
If you put a system in place to manage identity information like your HR system that people are trained on, has the proper security and backups and audit reports - you should reuse those systems. That way it reduces the chances of the data becoming misused or out of compliance. It also allows you to stretch your dollars because you can reuse the data you already are managing.
A virtual directory like Oracle Virtual Directory makes it easier to re-use this data because it can directly access the HR data without needing to copy it into another system. Thus your portals, single sign-on and databases can be deployed faster and more easily without having to worry about if the data is accurate and secure.