And this is why I am sometimes wary of engineers who cannot express themselves coherently in writing.
I've had people tell me I'm being "unfair" for saying that someone who can't write well about their work probably isn't producing very good work (and by "well" I mean clear, concise, and relevant, not necessarily aesthetically pleasing or grammatically correct). Apparently it's unfair because "not everyone is gifted at writing." (Granted, I am an professional editor, so I could be biased.)
But writing is, fundamentally, thinking. Not being able to write coherently about a subject shows an inability think coherently about it. So why should I trust people like that?