This sounds like a combination of a David Brooks column and a Robin Hanson blog post, and what could be better than that?:
Surprisingly, the most effective leaders did not have the highest level of self-awareness. Indeed, the more they underrated themselves, the more highly they were perceived as leaders. We assume this is caused by a combination of humility, high personal standards, and a continual striving to be better.
That is from Jack Zenger and Joseph Folkman, via the excellent Samir Varma.