I'm fine with your use of the regular CA/60, HDCA/60 etc. I don't think any of them truly isolate a players defensive game but they're at least useful. Where I disagree is that showing, and then ranking, relative stats has any value when comparing two players on different teams. The point of relative stats, to me, is to show how a player compares to his teammates. When you then take that number and compare it across teams I think you get some disingenuous results.
It's not just that one players relative relative stats compares to one player on a team, it's that they compare a player to an entire team as a whole and the specific players role on that team. There are things like quality of wingers and offensive D, etc. to worry about here but 1st line centers go up against the best on every team. (perhaps we should be looking at xGF% as a whole for straight 2 way play I guess)
What if your on a team with a crap D that gives up a ton of shots/scoring chances? Regular /60 metrics are not going to look good at all whatever you do as a center to try and mitigate them. When you look at REL numbers in concert with /60 numbers, and then compare the player to other players in identical roles around the league (1st line centers QoC are not going to be all that different), you'll get as close a comparison as is possible IMO.
Just going straight /60 biases things so badly towards players on good teams, it's hard to take them seriously on their own. However, if you your team averages far fewer shots and scoring chances against the moment you step on the ice, I think it should be acknowledged and taken into account.
I've already been told here that takeaways and blocked shots shouldn't be used when looking at defensive play. At least give me REL stats here.