bballman,
You’re correct that the fewer factors that get accounted for, the less precise any conclusion would be. But you’re also correct that Any data surrounding 3-2 counts might count for something. The problem is, it’s very difficult to get that data for any level other than MLB.
I hate to bring this up again because I know there’s a lot of folks out there who hate the thought of it, but until pitches not swung at are called with the same technology used to track where they’re at, it will literally be impossible to take into account the main factor that bears on what happens, the umpires.
You’re also correct that as of right now only MLB has the capacity to generate ACCURATE data. But just because there’s no way to get accurate data, it doesn’t mean all data pertaining to the topic is of no use. FI, it wouldn’t be difficult at all to compute OPB on 3-2 counts. That chart Everyday Dad posted was close, but it showed what happened AFTER each count, not what happened on each count. IOW, it appears that it only takes in what happened on each At Bat not on each pitch in a certain count. All those little things affect the numbers.
The more information about the subject, the easier it is to root out an answer. 