Now that you explained the ranks it makes more sense. And is similar to how I would rank things, but therein lies the difficulty of “ranking” prospects, since there are many variables at play. For instance an entire ranking could be of upside, or chances of making the NHL and how soon, or even based on floor. Generally I think that people tend to carry upside as the largest value in this, and NHL readiness gets a portion, though probably a smaller amount than it should given the ultimate goal of a prospect is NHL readiness.
A prospect that never makes the NHL is worthless, but one that makes the NHL in a throwaway role isn't much better.
For example, what's the organizational value of a backup goalie? Assuming a drafted goalie makes it to the NHL while he's still on his ELC or a deal of similar value, that's costing the organization $700k to $925k. Hutton, a proven veteran backup goaltender with good career stats coming off a pretty good year, was brought in last year for $1.125 million. On top of that, he even provided top 10 production at the position in the league for that price.
The acquisition cost for Hutton was nothing, the financial cost over the cheapest internal option was less than half a million dollars, and there was clearly legitimate upside there as well even if you couldn't count on it. Brian Elliott cost $600k when we brought him in. Clearly not all backups are going to perform like those guys, but you can generally count on the options being relatively cheap and easy to acquire.
Fourth liners are in the same boat. Every non-ELC who we brought in from outside the organization (i.e. didn't draft and develop) to play on our 4th line last year made $1 million or less. One of them was even on a PTO with Vancouver when we signed him. We had a pretty good 4th line, and we didn't need to trade any assets or pay anyone higher than ELC money to make it happen because it's not that hard to find 4th liners via FA, and they're cheap.
Bottom pairing defenders might cost a little bit more, but generally not much. Bortuzzo re-signed with us as a UFA for $1.125 million. The expensive guys rounding out bottom pairings are typically guys who were playing higher at one point who have been passed up on the depth chart (like Gunnarsson). I'd rank them as slightly more valuable to an organization than 4th line forwards, but not that much.
In my opinion, prospects who safely project to fill those roles (backup goalies, 4th line forwards, bottom pairing defensemen), but who have their ceilings relatively capped at that point, should never be ranked over guys who have higher ceilings but more bust potential because a prospect who has a 10% chance of being a top 6 guy still carries far more potential value to an organization than one who has a 100% chance of being a 4th liner.
The tricky part is weighing someone like a guy with 30% chance of being a top 6 guy and a 70% chance of being nothing vs a guy with a 10% chance of being a top 6 guy, and 40% chance of being a 3rd liner, a 40% chance of being a 4th liner, and 10% chance of being nothing. Does the extra upside outweigh the marginal value gained from someone who might be a 3rd liner? I think solid arguments can be made in either direction.