I think Bill George is absolutely correct about the importance of authentic leadership. However, I'd like to extend the discussion in a specific way by suggesting that it is the gospel that truly and ultimately brings authenticity into our lives and hence into our leadership.
The lack of authenticity in life or leadership stems from our fallen nature. We seek to obscure who we are, consciously or otherwise, because we find it difficult to confront our own fallen state. As David says in Psalm 51 - "For I know my transgression, and my sin is ever before me... Behold, I was brought forth in iniquity, and in sin did my mother conceive me".
Without the remedy of the gospel, we have no recourse. But in the gospel, we discover the both the gravity of our moral failure and the power of God's gracious love for us. We are freed to love and serve others rather than to live for ourselves. We are freed to lead, based on what is right rather than what is popular. We are freed to fight injustice at great cost to ourselves because we have a eternal treasure in Christ that transcends our experience in this life. Most importantly, when we fail, perhaps even in being honest or authentic, we can dispel guilt by remembering the work of Christ on our behalf.
For our sake, he made him to be sin who knew no sin, so that in him we might become the righteousness of God. (2 Corinthians 5:21)
Here's the point - authenticity means being who you were really meant be. The effect of Christ's saving work restores us to our Maker and frees us to be, exactly who we were created to be. Want to be an authentic leader? You might want to start by believing and applying the gospel daily.