Given that students are probably learning Python in university, I could see this being a strong reason for its growth. I hadn't thought of the "manager" angle - it makes sense that it's easier to plug a new developer into a Python codebase than it is a Rails codebase.
To me, Python's rise in growth centers more around its appeal to the Data Science community and the ease of non-programmer types to pick it up and use it effectively with a much smaller investment of training time. Ruby, although much more flexible of a language is much more difficult for a non-programmer to pick up easily.
