My view is that, to play the diamond, you need two David Villa types up front: strikers whose off-the-ball work is best when drifting into wide areas. You need that ability to stretch opposition defences so that you can create spaces in the centre, even if you're not doing much crossing, and both forwards need to be able to do it so as to keep the options as fluid and dynamic as possible.
Hence my view - expressed above - that we should play one up-top striker supported by Holman and Weimann, two players with the energy and off-the-ball nous to get in behind defences.
But it relies on having a robust MF three - hence KEA, Delph and Herd who are all energetic, good at covering and can also support attacks.