I think this is also a reflection of how difficult and competitive it is to reach the highest ranks in the US military. Because mistakes can be critical, it is a system that can be very unforgiving. Sometimes bad luck plops responsibility for the mistakes of others on an officer's blindside ruining a career. But, being perfect is no guarantee of promotion and thus you have people who will seek more education and study to help.

Unlike many PhD's these guys have to test what they have learned in a very unforgiving arena. The real question is whether the Congress will give them the time to make their case.