re: "Also, while some pronation can occur naturally, that doesn't mean that actively trying to pronate isn't a good idea."
-------As I mentioned, it is readily demonstrable that pronation must occur after the release of every pitch (using traditionally accepted mechanics). This is a biomechanical inevitability of follow-through that allows the throwing arm to wrap around the front of the torso.
As I also mentioned, presetting pronation of the forearm, wrist, and hand is necessary for screwballs and most types of quality changeups. There is no clear way to throw an acceptable fastball, curveball, or slider with preset pronation (although I wouldn't be surprised if cult leader Mike Marshall claimed there was). Since pronation does occur after release of each and every one of these pitch types, it is unclear to me why pitchers should "try to pronate". One might as well counsel bears to cr*p in the woods...they are going to do it anyway.
In fact, an emphasis on "trying to pronate" is truly misguided because it takes away focus from the importance of learning how to properly release curveballs and sliders. It's not the stuff that inevitably must happen after release of those pitches that is important to work on, the training point is to grip and release those pitches correctly so that there is not more resultant stress than necessary from them as the pitcher goes into inevitable pronation.
In my opinion, Chris O'Leary is still tooting Marshall's horn here...i.e., Marshall has been trying to "sell" pronation as something he personally invented for years and Chris has fervently bought into Marshall's various claims for years. Mike Marshall also claims that Isaac Newton's Laws of Motion are uniquely on his side and that only he can guarantee 100% injury-free pitching at the highest competitive levels of baseball. Pure voodoo cult stuff. Absolute drivel.
Chris, you've said a couple of times now on various forums (including this one) that you have recently "distanced yourself" from Marshall. On the other hand, a brief perusal of your website shows that you still claim to be "40 % influenced by Marshall", whatever that may happen to mean. But, regardless of what you mean, that number hasn't changed for years, nor has your enthusiastic "Marshall 101" short-course, wherein you purport to teach Marshall's mechanics ideas to "ordinary people".