Schools comparable to Berkeley have one of three common organizations of math teachers. One, Berkeley's old structure, is to employ no lecturers. Another is to employ a lot of lecturers, whose job is simply to teach as well as possible.

But I think the most common organization is to employ a small number of lecturers who do a small amount of teaching, but whose real job is to handle the administrative details of teaching, such as placement of freshmen, curriculum design, and instructing graduate students in teaching. I think the complaints make most sense in the context of the department expecting him to grow into such a job.