First thing, it seems you're assuming I accept the concept that a "riseball" for example cannot be the "fastest pitch". I do not believe that. I do not think there was a distinguishable difference in my own personal speed of my drop and rise. On any given day, one might me 1-2 mph faster than the other if I was throwing both at max speed. I would and could vary my speed on the drop (changing speeds, not changing up) but would not do that on a rise. Anyway... in all of the scenarios you described @riseball, the key was the sentence you said about all the pitchers having same spin and downward movement: then they're all throwing drops!! If you wanna rename it to a fastball, go head. If you wanna rename it to the MLPS, go ahead. But at the end of the day, what you described with movement is a drop. My entire point in this is: if you have a ball with 12/6 spin and movement, why would anyone need another pitch that doesn't move?
I wish I could tell you how many times I've given up HR's and tried figuring it out in my head and mechanically between innings "Why won't the ball move today?" Some days the ball simply dances. Other days it stays flat and I'd pay the price. I simply cannot fathom a pitch that doesn't move on purpose. It makes ZERO sense.
If she's got 12/6 spin but no break, it's likely the release point. Fix that, get the ball dropping. In all the BP I've ever thrown to college age hitters from mid majors to Power 5, the drop is the pitch they struggled with the most.
Back to my original question:
...I would love to know the specific spin, axis, and movement that universally defines a fastball ...
It would seem in your case your fastest pitch on any given day is your rise and/or drop. So based on the conventional definition of a fastball being your fastest pitch, your rise and/or drop is also your fastball is it not? Or are you redefining a fastball to be something else possibly just a pitch that does not move? In which case how is the speed of the pitch relevant, isn't it just a bad pitch? While I agree that most successful pitchers do not at least intentionally throw pitches that do not move (bad pitches). It seems counterintuitive that successful pitchers do not throw their fastest pitch. Why would a pitcher not throw their fastest pitch (fastball) if it happens to be a rise and/or drop if it has great movement?