my observation about why some elders are great and others are not is about accomplishment/achievement/ego
Maslow says that we all need to feel achievement - when men do not meet that need outside the congregation through work or other accomplishments, then their "need" for it within the congregation is more desperate and because they are insecure, they tend to wield what power they have with a heavy hand.
The men I have known who are mild, balanced and kind elders usually have other accomplishments and are secure. They were business owners, artists, or wealthy - they had already had an area of accomplishment in their life, and felt respected.
It is the most insecure, emotionally unstable men who seem to be unable to apply Bible principals as they were intended because that would not align with their need to feel better than a "sinful" or "bad" person.
Just my 2 cents.