Recently, I have gotten back into thinking about Mark Prior, his pitching mechanics, and how they developed.
It started with this clip, which shows a professional pitcher making the Inverted W -- a generally moving pretty much identically to Mark Prior -- without trying to.
Minor Leaguer in 2012
Then, in early 2015 I stumbled across a clip that showed a young pitcher moving the same way.
The interesting thing was that, when I talked to his pitching coach, he said he doesn't teach the Inverted W and doesn't like it when he sees it. Regardless, his student still makes the Inverted W.
That makes me wonder whether Mark Prior's problems resulted in part from things that made him, perhaps inadvertently, make the Inverted W.
Arm Action, Arm Path, and the Perfect Pitch page 48
I believe the image above, which is from Tom House and Doug Thorburn's Arm Action, Arm Path, and the Perfect Pitch holds the key to solving the problem of Mark Prior and why so many pitchers still move like he did.
It sounds like Jim Benedict, formerly of the Pirates and now with the Marlins, has bought into this. Which is too bad for the Marlins. http://www.piratesprospects.com/2015/03/the-evolution-of-jameson-taillons-delivery.html