John Sickels has up a Prospect Retrospective on Mark Prior from this afternoon.
So was it all Dusty Baker's fault? Well I'm sure the way Prior was used in 2003 was part of the problem, but I don't see how it can all be laid on Dusty. As I wrote in 2006:
It should be noted that Prior was a California high school pitcher and a California college pitcher: he has more mileage on his arm than a lot of pitchers his age. "Flawless" mechanics or not, his health problems have not been out-of-bounds from what you'd expect given his background
And of course, in retrospect Prior's mechanics were not flawless, at least if you buy into theories about "Inverted W" arm action and excess scapular loading.