Overproduction vs rate of profit?

I want to understand more about these two crises of capitalism. How do they happen? How do they relate to each other?what is the context on the debate in leftist circles around them, as I know some groups prefer to emphasise one over the other. I have read a bit on Michael Roberts' blog, he definitely prefers to emphasise the falling rate of profit but some of it goes over my head.

Any books/articles on this stuff that comrades would recommend?