I'm not banging a drum and insisting that they draft Singer 9 months before the draft is held, but you kind of blew past some details here. The most innings any of Brad Brink, Tyler Green or Pat Combs pitched in their draft year was 125 innings, so they weren't ridden particularly hard by their coaches. If you want to get into that these guys were worn down by 'extra' pitching on the cape and Team USA, I can buy that.
Singer pitched as a reliever his freshman year, pitched like 120 innings this year, and was given the summer off. Hardly being overused.
Tyler Green struck out 14 against Creighton, he pitched 9 innings. The Phil's scouting and player development during that era was hardly a successful group to be able to point a finger at their college coaches for being the reason these guys didn't make it.
Pitchers as a whole are a gamble. There is an inherent risk factor. All things being equal, take the position player. But when all things are not equal, you have to take a shot at the elite arms. 'Never draft a high school pitcher' #1 and you never get a Kershaw, Bumgarner, Carpenter, or Halladay. 'Never draft a college ace' and you never get a Price, Cole, or Lincecum.