I didn't live through Clough, but you look at footage etc.
What strikes me with him are two things. Firstly as you say a complete maverick. The very best people, the genuises amongst us don't follow rule books or guides, they write them with how they do it. They set precadents etc. You always get the sense he did that.
The 2nd is his old idiom of football being a simple game made complicated by idiots. It's true of football and it's true of life. The amount of people I have worked, for, with, alongside, coordinated myself etc, the ones who can talk and act with simplicity stand out. The ones who have such an understanding and confidence to convey messages in a simple way stand out. He could do that. It's a great mantra for everyone.
We live in a world now, where we all want massively complex discussions on things, and people see themselves as making an impact has to be either a big thing, or a very complicated one. Just see what is simple and do that. Clough embodied this to me.