How about Victory Ratio, or the frequency with which a character's "build" wins the (exact) desired outcome in a situation?What other ways could we, if so inclined, discuss character ability to move or shape a game other than DPR/DPS or whatever? No we don't have to...but for fun, how would we quantify it? What areas would be included? I am struggling to think of something as succinct as DPR/DPS perhaps because of the variability in actual play. But it seems that accessing, acquiring and avoiding targets and danger should be as important as DPR or whatever.
This reminds me of setting goals / KPIs for my employees. HR keeps on about measurable goals - but oft times what you want to encourage and reward aren't measurable in terms of here's an objective number. If I have one guy who's always dependable, will work the hours needed, and will stay with a problem with the tensity of a bulldog, what's the objective measurement I can put in vs. the guy who cherry picks the easiest tickets and turns in more of them than anyone else?
So white room DPR is something easy to calculate and compare, but just a portion of what we're looking at, just like number of tickets is a poor indication. It's the parts that are harder to numerically evaluate, or even more, vary by DM and table, that oft get overlooked because they aren't easy to evaluate.
D&D is (nominally) a game of resource-management, so the obvious metric for utility abilities is in how many resources they conserve. If you can conserve two low-level spell slots and 30hp by talking your way past a fight, then you can compare that to the 15hp that the barbarian's power attack saves by ending the fight one round earlier, and it's obvious that the first ability is better in that instance.
The problem is that, in practice, the resource-management aspect of D&D is irrelevant. You get all of your HP and spells back every morning, and the party will call it a day before they actually run low enough that it would affect their performance, so it doesn't matter whether or not you conserve anything by bypassing a fight. In fact, it feels disappointing to go to bed with all of your HP, because you know you were playing too conservatively; you should have been able to accomplish more in a day, if you had actually expended your resources rather than conserving them (whether or not that's actually true).
I would say that building a character only geared towards combat is a "trap option"
I recently made an EK/hexblade. In general the gish needs his magic to make himself better in combat, but I made sure to take some spells and invocation that had utility too. Find familiar, suggestion, illusions... He could have been more combat focused, but that is less fun overall imo.