The political fault lines he's describing exist at every flagship state public university, and so I'm not at all surprised to hear that a quake has happened along those lines at Berkeley.

But also most performers have a flair for the dramatic, and Coward's excellent student reviews seem to come in part from his talent at performance. So his interpretations are likely massaged in some form, and the object-level claims could be easily exaggerated.

But he claims that he and the department differ on a fairly simple statistical claim--how to estimate the effect of his courses on students' future performance. The related email correspondence is here, and well worth reading, both to judge that specific matter yourself, and get a sense of how defensive Coward can seem. (He's definitely escalating emotionally, but justifiably is harder to know.)

My summary: In a report, Stark, a statistician, makes a three-way comparison between the three 1A classes (two of which were taught by Coward), and finds that they are not statistically significantly different. Coward asks why a three-way comparison is done, instead of comparing the Coward group to the non-Coward group. Stark replies that since the students were assigned non-randomly, we can't separate the direct effect of instruction from any confounding variables.

Which is, of course, correct--it's very likely that the students who got into the class with the instructor widely believed to be superior by students are more competent than the students who didn't, and so should be expected to do better in future classes--but an equally valid point against the three-way comparison.