Skill determines the top 30 but making 30 the cutoff isn't based on skill. Equal parity in the league is a misnomer because if one team's top center is way better than another's, that's not equal, regardless of how well the talent is distributed throughout the league. If there was 29 centers roughly equivalent to Sidney Crosby in the league and then the next best center was Ryan Kesler, it makes no sense to suggest that the team with Ryan Kesler has a number 1 center. Obviously that's an extreme example, but even as it is, when looking at the 30th best center, you're looking at guys like Turris, Little, RNH, etc. There's a significant difference between them and the Crosby, Giroux, Tavares types, and it means a team with one of the first group as their top center needs to be significantly better at another position to make up for it. If you don't feel confident that your best at a certain position can come reasonably close to matching the best of most other teams, you don't have a number 1.