I'm not really a believer in the "top-x" players as a means of evaluating whether or not a player is a good 2C or not.
There are 30 teams, but only really 5 or 6 that are true cup contenders. Given that the goal is to try and build a cup winning roster, a 45-point 2C is okay, but not "great" when compared to the likes of Bergeron, Carter, Malkin, Couture, etc. We might be able to get by with a 45 point 2C (like Bolland/Shaw with Chicago) but that would require us to be even better at other areas of our roster (i.e. have a defense pairing like Keith-Seabrook, have a talent like Kane on the 2nd line...)
But ideally we'd want a much better player than that to centre the 2nd line from the perspective of building a cup contender, regardless of who the top-30 scoring centres were.