That moment when you read in BDAG (and BAGD, too) that σκοτίζω’s middle form has the function of: […]

Transitivity plays a central role in all voice usage, not only in the contrast between active and middle, but also within the usage of the middle voice itself. Understanding that range is important for discerning the meaning of a given verb in the middle voice when reading the biblical text or other contemporary Koine Greek literature.

Ἐργάζομαι is a bit of a difficult verb to deal with in terms of voice. It’s perhaps the only verb that causes problems (at least at face value) after the rejection of deponency as a valid category for the Greek Voice System. Rutgar Allan categorizes it as an indirect middle (Allan 200, 54). That has always seemed a bit forced. But perhaps there’s some credence to it.