I may of missed you replying to this but as others people said, "hardcore" "casual" etc, is ONLY time spent, not skill. Logically more time spend on something the higher skilled they are but that is not always the case. Such as:
Neither, I do not see 3 or 10 hours a week a line to define hardcore. if they where doing 5 hours a day, sure, hardcore it is, regardless of the progression.
Oh it holds true alright, let me explain a personal exmaple of that 230 average bowler that does not want to do leage. If you know what to look for, even with out parsers, my friend which I do expert with almost daily will point out flaws in a person's up time or rotations no matter how they are greaed. She always throws tips for me and others in regards of scripts, so you are moving a head of time before you see the move, and with my lag issues time to time, it is very helpful. This friend however don't do savage even though i'm sure that they are quite able to handle it. why? because we both believe that gear get replaced too fast, making it feel overall pointless, and that she's a very hardcore crafter who enjoies it more than doing savage. I might that she might even be crazy hardcore one also, insane playtime with gathering and crafting at times, if motvated. She can grind for long periods of time like how i even remember her getting 2 lvl 60 relic in under 10 days during HW.
I said earlier logically, hardcore players SHOULD be more skilled then casual, due to the greater time investment, but its not always the case. Also one more thing, you can be high skill without ff logs, leads me to have issues with this sentence:
" FFlogs starts to record from high midcore on in my opinion; that's when the focus moves beyond clearing to optimizing and ranking"
Stop trying to pigeon hole people, the skill one does with keeping uptime while doing mechanics is not defend by if a player does savage or not. That is a schedule cooperation, nothing to do with player skill.