Players seem to change so much during games, let alone during a season or career, that it's hard to nail down.
It's not like the discussions we might have had when Neitz and Schwarz were going around, in which there seemed to be more consistency of roles, and discussions going back further than that in which players generally kept to a position.
Add that to the fact that Cook hasn't debuted and Howe has only played a couple, and thus it's tough to have much great insight into those guys unless you've been getting to Casey games regularly, and it makes it even tougher.
That said, Jurrah predominantly close to goal seems the way to go, although his delivery into the 50 can be very good.
Cook seems to be suited to pushing up the ground and playing as a lead-up 'CHF' type, based on what I've read of his Casey adventures.
I would have thought Howe might be nice playing a bit closer to goal, while I'm not sure about Watts. If he was to play a CHF-type role I'd like to see him kicking the ball longer when he wins the footy on a lead, whereas his preference now seems to be shorter kicks.
As others have said, I agree that having a tall target deep would be nice. DB has also said this, so I'm sure we'll see it a bit in future - particularly if Martin can at least provide a contest deep in the way that someone like Ben Holland did.