A pushback on fruitfulness

Paul Levy
To say I have no interest in Old Calvinism/ New Calvinism, New School/ Old School is a colossal understatement. It's not my fight; not once has it even crossed my radar in ministry, though I realise it's been a big issue for Walker down in Crawley!!
I read Rick Phillips piece with interest particularly his strong disagreement with Tim Keller. However I would want gently to disagree with Dr Phillips strong disagreement. I confess, I  haven't read Center Church.  For me the actual shape of the book is a huge turn off. Books should be made to be held.  When I've looked at Center Church it's just the wrong shape for a book with odd columns.  I've read quite a bit of Tim Keller and couldn't tell you whether he's Old School or New School and my suspicion is neither could he.
Anyway I am puzzled by the concern that Dr Phillips' takes regarding fruitfulness as the measure of ministry. I hear Rick's alarm bells at New School revisionism, whatever that is, but surely we are called to some form of fruitfulness. Obviously, that doesn't equate exactly with growth in numbers, but a healthy tree or plant will be fruitful. Faithfulness and Fruitfulness must never be divided. Who has ever heard of a healthy tree that doesn't bear fruit - whether that is an old school tree or a new school tree?

John 15:2 - He cuts off every branch in me that bears no fruit, while every branch that does bear fruit he prunes so that it will be even more fruitful.