This is actually a well thought out metric in principle. However, if you tried it in reality you would get awful results.
We set out in this conversation as if guys like Boqvist or Zadina do have top 15 in their position potential. I don't think they really do. At any time, players from roughly 15 drafts will be active. Not every single draft has a top 15 player at their position. Much less one who is considered a top prospect in their draft year. Seeing that Dahlin and Svechnikov are the top Dman and Winger in the class, if you chose either a winger or a defenseman you'd already be picking the 2nd best defenseman from that year. If you draft purely on superstar potential you really end up eventually drafting like an NFL team, picking someone like Dobson in 3rd, Serron Noel in 4th and K'Andre Miller in 5th. Choosing players almost purely based on raw speed, athleticism, and cerebral nature. You might get lucky a couple times. You won't most times. So depending on what the draft gives you, sometimes you've got to just settle for a really good player.