Expanding on the TACKLE model presented in Unified Theory of Software Development.
Hypothesis: at the beginning of their careers (and perhaps well into them), most software developers think written/verbal language skills are of little importance to their field. To the contrary: as with most science and engineering fields, where language arts and communications classes are seen as secondary at best, the truth is that communication skills are critical to success. Being "coherent" means that one is able to express himself in clear terms, logically and consistently. This ability is essential in both code and "regular" language.