I have no hard evidence, but from a business perspective I have figured that one of the main appeals of Python is the combination of simple and strict that defines the community. Some languages (cough Perl cough) are practically art, and that frequently translates to a steep learning curve for new developers to a project, which in turn means cost to the business. Bringing on a new developer to a Python team feels like it involves a much shorter time-to-productive transition period. As a manager that makes me biased towards Python for workloads where a scripting language makes sense.
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.
