Last night I think I cracked the code on breaking down the constitution stat. There's still a lot of work there, so I have nothing to show today. Still, the goal is to apply the same construction to all the ability stats, with time, so for a moment I wanted to talk about dexterity.
Dexterity is an odd stat. While it belongs, and it's physical like constitution and strength, dexterity has a strange quality in that it is potential ability in so many aspects. We teach people how to manipulate objects and play sports, or how to play musical instruments. To some degree we do these things on our own, but real facility at something requires training. Children's games build on this, as so many of them are designed to challenge our dexterity by training our hand-eye coordination. No adult invented dodgeball. It is a game that grows out of the much-less-pleasant dodgerock, adapted by cruel educators to teach both dexterity skills and the realities of social abuse.
In separating a 12 dexterity from a 13, it is much harder to do that from a visual standpoint. A more nimble person might seem properly more lean as their dexterity increases, but we have plenty of celebrity examples to show that's not necessarily true. Large, bulky persons find tremendous comic potential in being both gigantic and profoundly agile.
The truth is, the difference between a 12 and a 13 is in their potential to shine once introduced to a skill. The 12 dexterity might barely survive in double-A baseball, while a 13 will do all right. A 14 will drift back and forth between double-A and triple-A, while a 15 might imaginably dream about playing in "the show" for as much as a week, if the Boston Red Sox suffer a lot of injuries. All these players would look similar, with like body-types, reach, stance, even the way the walked. But they wouldn't be the same.
So how to measure it? Probably, by defining different qualities related to those things that can be taught. What dexterity do you need to snatch a baseball out of the air one handed, or target a football while in mid fall, with a tackle's arms around your waist? Or, in D&D terms, what is the minimum dexterity for using a bow? Throwing a dagger? Jumping 10 feet? What level of dexterity do you need to so that you don't need to make a check in order to climb a ship's rigging? In a storm? When there's ice on the ropes?
The reader should know I hate random checks to see if someone who can jump 12 feet might manage to jump 15 just this once, because that's the difference between ledges. I loved track and committed to it throughout high school, but long jump just wasn't my thing. I could jump 12 feet 1 inch, or 12 feet 4 inches, or 12 feet 5 inches. Three more feet might as well have been the moon. It wasn't because I didn't have the potential. Long jump requires training to get past what we can do with physical force and will. There's a way of jumping off, of hitting your last step perfectly, of throwing your lower body forward as you swing your body in the air, of "running" while flying. It is a spectacular ballet. It doesn't happen naturally. The coach tried hard to communicate it to me, but I just couldn't figure it out.
Without that connection, having failed that training, I'm not going to suddenly be able to jump three more feet because the die says 20. It is one of the silliest notions of 3rd edition mechanics, as it insists we ignore everything about reality.
I'm not fond of measuring anything with a list of stuff that a person can and can't do, as it is never a complete list and the more things added to it, the more arbitrary the list becomes. I'll need to do a proper amount of research to learn if there are any measures on agility that already exist ~ people ARE researching this stuff, we don't have to make it up out of whole cloth. For the present, I'm puzzling it out, asking questions and identifying the problem. That's the first step.