> But are language enthusiasts really better hires in general? I've known many of them who loved the theory and toying with a language but were not any better at producing actual value than the average joe.

I think they may be safer hires, anyway. They will be able to program themselves out of a wet cardboard box, which is more than you can say about the average Joe who may just be good at bluffing the interview.

I have noticed a lot of language / framework collectors where every new project is in a new framework or language on their CV. While it will expose you to a lot of different ideas I doubt you will code very well in any of them if you are swapping every year. I have seen plenty of Python written like its Java and its just less elegant code. And Django code that doesn't follow best practices seems to be the norm. If you take the time to master a few things you can produce some quite elegant solutions. If you only know the basics, you reinvent the wheel in a crappy way usually.

In my experience they're quite correlated (but not 100%). It seems to be a strong signal for passion about development, which I'd say is important for hiring someone who really cares about doing their job well (which I also find is an important and rare attribute in a good dev).

That's what a good manager is for, they're there to turn a powerful engine into a productive one.

I think this depends on what you mean by “actual value”. A working product powered by a tangled yarn of hastily-assembled spaghetticode has a highly dubious long-term value, and what’s worse, your “average-Joe” coders might not even realize/see the value of what that “one overly-careful coder” brings to the table

They're a great way to seed your recruiting pipeline. Enough of them ought to be good hires to make this useful. After that, you just have to trust your hiring process, just like you would for any other source of candidates.