Generally, we do not present ELA results in this report for two reasons. First, the variation in effects among ELA teachers is substantially smaller than that among math teachers. This finding is consistent with other research on teacher effects and may suggest that other factors outside of the classroom have a larger influence on children’s ELA performance than is the case in other subjects. Current research also suggests that ELA state tests may also be less sensitive to instruction. Second, we do not present results among ELA teachers because, in most instances, they are very similar to our findings concerning math teachers (though some are smaller in magnitude). We explicitly make note of instances where ELA and math results diverge.
That's a big asterisk. History, social studies, science (esp. elementary school science), the arts, and pretty much everything else you want to teach is more like ELA than math.