Productivity in software development isn’t controlled just by the individual, it is controlled by how several individuals interact with each other.
….
Yes, individual programming skill matters greatly. So does the ability to work effectively with others. It’s not either or, it’s both. And that’s still not enough. To be productive, programmers need a supportive environment, and I don’t mean (just) nice colleagues. I’m talking about being in an organization designed to maximize the effectiveness of those who work in it.

and from the comments, Bob Marshall/ Deming:

“some 95% of an individual’s contribution is a function of the system that they have to work within, and only some 5% is down to an individual’s innate talent and effort”