Have said it elsewhere but essentially:
Every pick is either a cash cow or a keeper, anyone in between those two things is a bad pick.
When assessing a midpricer I do, keeping it short, essentially 3 things.
1. Can they be a keeper? A yes here puts them in play no matter what. If I think they're likely to be a keeper then they're hard to go past.
2. Can they average +40 on their starting price and match a mediocre rookie? A yes above and a yes here puts them in the "why not pick them?" category. A yes only here has the question of can I get the same from a rookie? Is their JS/role that much better.
3. Can they put up massive scores that spike their price? Ben Brown was a great example of this. I don't think he's a yes on either of the above, not a firm one at least, but I do think he can score a couple of 130 type scores in a month, which has the effect of averaging significantly more. Basically it's the other way to be an effective cash cow.
Assessing on these criteria...
Ziebell - Yes, can be a keeper, ~95 average twice before in his career and if he has the role change I really like it for him. I don't think it's likely. Yes I think he can average 40+, he's priced at 48, has averaged 88+ 4 times and 84+ 3 times in the 7 seasons prior to LY, I think it's likely. I also think he's capable of big scores, especially if playing as a rebounding defender, this is also likely. So while I'd be picking him expecting a rookie, there is a glimmer at least.
Milera - Yes can be a keeper but I think it's quite unlikely. Priced at 58 I think he can do 40+ but I think it's quite unlikely. He can put up decent scores but I'm not sold on big scores. You'll notice here that 1 and 2 overlap, if he makes 40+ he'd be a keeper. Given I think it's far less likely than likely, he hasn't sniffed my teams but his position at least makes him a chance.
FWIW, Preuss I think is a solid 1. No 2. Yes 3. Yes which makes him a perfectly reasonable pick and I'm genuinely considering him at R3 at this point in time because I think he can make 200k (I like Gawn and Grundy as starting picks so it's R3, if something changes there, R2 comes into play). I don't like having a dead bench spot, you're handcuffing your cash generation, so he's in play, question is can I use that 200k elsewhere for genuine gains?
Heppell I think is a 1. Yes but very unlikely. 2 Yes 3. Yes. Again making him a reasonable pick. At his position though I think there will be enough 125k options with similar prospects that at this point he's unlikely to be in my team.
Then you have guys like Taranto who'd be a 1. Yes but unlikely, 2. No, 3. Yes but very hard to trade if he does. That puts him in play but makes him risky given I don't think I have the discipline to trade him if 3 happens before it has run out. Most of his price group fit that.
Rozee is a Y, N, Y guy as well but I'm not particularly sold on him still. Jeremy Cameron in the same boat. They're probably in the same place as Taranto, I'm not terribly convinced on the first Y and I'm not sure I have the discipline to move them if 3 happens because god I'd hate to move them and it turns out the first Y was correct!
Then of course there are guys like Franklin who is obviously a Y, Y, Y guy and yet I haven't thought about picking him to this point. That said, if he was there for round one you have to think about it.
This year I think the midprice crop is actually very thin, Preuss if he was a R/F would be a lock for me, alas, he's not. I just struggle to see many that are well balanced keeper chances that can not get there and still succeed because the vast majority are in the 75+ pricing range where it's keeper or bust and the odds of hitting in that group are just not very good. Last year on the flipside was a great year with a lot of decent options. Perhaps the preseason games will change this. Someone like Toby Greene playing midfield for example would shoot to my first picked forward.