Over at Royals Review, there's a lengthy look at the success rate of prospects ranked in BA's top 100 prospect lists.
It is very detailed, with lots of data, and takes a look at success and bust rates for prospects by position and by organization, among other teams.
I think most people here won't be surprised to learn that, for the period in question (1990-2003), the Texas Rangers had one of the highest failure rates in baseball, with only three teams being worse in that time frame.