great reads, Blue.
I did a lot of posting about slotting in a 6th starter every time the rotation goes through 3 turns or so without an off day. Something like that was mentioned in the Stark piece. Also the Sale plan looks interesting, and Don Cooper has a great record for rotation arms.
I once had a talk with an expert on large industrial accidents who used to joke about his job being to try to fit curves estimating the frequency of huge chemical spills based on one or fewer data points (i.e, Bhopal). The answer in that case was to look at lesser events and the things that prevented them from being major. With baseball pitchers, it may be the case that there are indicators of stress on arms or ultimately surgery from more pitchers than just Josh Johnson and Kerry Wood. Toss in the solid data from younger arms and there arm probably ways to infer how that data relates to slightly older but not fully mature arms of 23 year olds.
I think Stark probably understates the data Rizzo is drawing on. That is one factor. Also, Rizzo's goal as a development guy is to optimize his talent, and I think that makes it easier for him to go with the recommendations from the sports med guys.