I also work with someone like this. They get jobs easily because they nail interviews and talk intelligently about problems. But when it comes to implementing

I also work with someone like this. They get jobs easily because they nail interviews and talk intelligently about problems. But when it comes to implementing actual code to solve real world problems, he can't scale it intelligently at all. Duplicate logic all over the place, hard coded values, refusal to research and use frameworks' best practices...it's all there. It's incredibly frustrating, and because he's so knowledgeable, it makes him even more stubborn to constructive criticism. Many times his arguments boil down to "I don't feel like doing it that way", in the face of valid arguments. The facts remain, his code is difficult to maintain, difficult to scale, and buggy.