Well here is my list reason why leader fail or plain stagnate. I've now seen leaders do all of these. Some of them in secular settings as well.
1) Great bloke:: Bit of a personality, But just interested in keeping people happy. They are mediation experts. Usually don't end up changing anything or going anywhere. Will usually water down a difficult message if they know it could 'offend' people in the crowd.
2) Not really liked:: Good teacher, speaker, has a bit of a plan. Yet has burnt to many bridges along the way. People just aren't willing to give to much of where this person is going.
3) Insular:: Has loaded the leadership team with mates. Yes men. When really a few dissenting voices can sharpen and give clarity to leadership ideas.
4) No direction::At times it is easier to just go with the flow a place has alway gone than to change things for the better.
5) Innovation of others:: Inability to accommodate others ideas. Usually the excuse is. 'It doesn't fit in with our vision, mission statement. The leaders wiill not tick it off even if it is a 'Kingdom' idea.
6) inability to get anything off the ground:: All talk and committees. Yet a few years on, nothing new has got off the ground.
7) No personal accountability:: Good mentors, good mentors, who will ask any question.
8) No financial accountability:: Yep I've seen a few churches blown off the earth with this one. Make sure people are asking question, even ones you don't like.
9) A constant learner::You know the people who are at the edge of stuff. They will know and have read what is currently top of there profession. Not just profess an opinion because they spotted a one liner from twitter or a blog. I've tripped up a few leaders by asking the question when they throw out an opinion "have you read the book?"
After a while the people you are leading will pick up on this....
10) Know the gifts of others in your team:: You can spot this one because the leader usually does everything. In some ways its easier to do it yourself. You don't need to ask anyone then. Yet its a great disservice in trusting others, and letting them grow.
11) No guts:: Not really willing to put there position on the line even if they believe in something. To many ministers are still in the job, because it is the only job they know.
12) Don't know when to call it quits. Has done some good stuff, yet a few years latter things are stagnate and not looking any better. Its better to leave saying I've raised the bar than seeing it raised then slowly fall.