There is some interesting research currently happening that questions whether there is such a thing as deponency. For example, many deponent verbs are intransitive (36.10) and therefore cannot be passive. See the class website for an ongoing discussion.
I join those who feel that the notion of deponency in Greek is problematic, and I will be instructing my class that the so-called deponent verbs should really be thought of as (inherently) middle verbs.