Average Leaders vs. Great Leaders

What is the difference between a great leader and an average one? Many things of course, but here is very poignant assessment taken from a really good interview about Good-Enough Managers:
Average leaders generally have mediocre engagement and don't have much sense of ownership of their organization. Their team is not motivated, and they tend to deliver whole periods of not terrible but not great results. They basically keep going, not pushing boundaries and not raising the bar. They don't get obsessed with improving results and performance and creating an atmosphere where people can perform at their best. But they don't get much attention because they're not messing up.
(HT: my brother Jeff for sending me the link to the article)