Ruckman are always a risk. Rarely do they go early in the draft (Jackson and NicNat are exceptions), and you can get a good one at pick 30, or pick 103. Nobody at 18 at 200cm and 9kgs soaking wet is going to show much more than some baby giraffe like athleticism.
You gotta keep taking punts on these guys and see how they turn out. Low risk but high reward type stuff.
We have had decades of being blessed with really phenomenal ruckman from Stynes all the way to Gawn and now Grundy. That doesn't mean we have to have another one in the ranks, as many teams have won flags with ordinary ruckman. It's just about how you play it.