I'm really enjoying Doug Chaplin's blog, which I only discovered a month or two ago. He's just put up another fascinating post on why it's barking mad (my phrase!) to try and read the New Testament without paying attention to the Fathers, who first read those Scriptures, and indeed decided that they were Scripture in the first place! On the question of the development of priestly roles he writes "...there is nothing clear in the text of the NT that either prevents or criticises the linguistic and theological moves attested in the very earliest of patristic writings, and subsequently developed over the next two centuries. Those who read these texts written in their own language, recognised them as scripture partly through their consonance in the same faith, and collected them and canonised them as part of that same inheritance, are the same people whose reflections on ministry in the light of that slowly forming canon led them to a theology of priesthood dependent on and reflective of the true high priesthood of Christ. They almost certainly offer a surer guide than those who, fourteen centuries later, mined the same scriptures for their own polemic against mediaeval developments."
This quotation applies to the development of the priestly office (indeed the entire three-fold ministry); it also applies, inter alia, to the baptism of children and - though I hesitate to mention it - the doctrine of penal substitution which was virtually unknown in the Fathers. This is an area where I have qualms with the anabaptist arguments, which seem to run together developments post-Christendom with developments in the immediate post-apostolic generations. To my mind it's essential to separate those two things.