Technique can only make us orators; if we want to be preachers, theology is what we need. If our theology is right, then we have all the basic insights we need into what we ought to be doing, and all the incentives we need to induce us to do it faithfully.I want so badly to say that it's both/and. But I'm not convinced it is actually true as a both/and. We make too much of 'able to teach' as a way of encouraging great orators, and though we think we're serving ourselves, we are on the whole much the poorer for it.
We all know it's possible to be a great speaker, but not a great preacher. And yet it's equally true in reverse, though we're reticent to say it: it's possible to be a great preacher, but not a great speaker.
I would not class my soon to be retired principal as a great orator. But he is indeed a great preacher. Substance is a style.