I have put together a number of pieces that analyze Mark Prior's pitching mechanics, in an attempt to identify the aspect(s) of his pitching mechanics that contributed to his problems.
One common objection to the idea that Mark Prior's problems are related to his pitching mechanics, and to the Inverted W, is that Mark Prior's case is confounded by the fact that he had a collision with Marcus Giles in 2003 while running the bases. While it's highly debatable that Prior's shoulder problems were related to that collision -- Prior didn't start having shoulder problems until more than two years later -- the case for the Inverted W doesn't rest solely on Mark Prior's experience. Instead, there is another pitcher named Anthony Reyes who had the same pitching mechanics and who also had serious elbow and shoulder problems as a result.
As it turned out, while Anthony Reyes lasted a bit longer than Mark Prior -- presumably because he wasn't abused as much as Mark Prior was -- Reyes eventually went down with simultaneous elbow and shoulder injuries that he never recovered from.