I don't watch minor league baseball although I've started to follow it closely since 2010. Most of what I know I learn from this site, so I'll try not to repeat what other excellent posters say. What I'll offer instead is an argument that doesn't get enough attention, in order to show that Scott and Keuchel are underrated prospects (granted, their 2012 should have everybody eager to overrate them after ten days!).
In the fan poll, DK was the #26 prospect and JS wasn't in the top 30. Granted, they're two very different prospects in terms of age, (24 vs. 20), level (AAA vs. A) and position (P vs. OF). Still what they demonstrate is the ability to produce the same peripherals as they move through the system. And the ultimate argument against "low ceiling" guys is that their game won't "translate" at the next level. One (granted only one) way to measure this, is to see how it translates from one level to the next.
First, JS: he hits .300 at every level. Granted, he doesn't slug a lot, but power comes last, right? In 2010 he played in the GCL and hit .301. Then he moved up to Greenville and hit .323 in 2011. In 2012, he essentially skipped a level and is crushing it. He won't hit .400, granted, and he only has one double to go with his singles, but he's showing that he can be a .300 hitter while very young, at every level. He hasn't needed a lot of time to adjust.
You get the same thing with Keuchel. At every level: a very good ERA, strong control, and a 3:1 K/BB ratio. Granted, he's struggled with mid-season promotions, both in 2010 and 2011, which was much more alarming, when he was a mess at AAA (7.50 ERA, 12 bb , 15 K in 36 IP/ 7 Starts). This year he's been perfect.
Tools matter. Gaudy K numbers and power potential say something meaningful. But so does the ability to succeed at every level, as you move through the system at a steady pace. DDS has a better shot to be an All-Star, but I'd bet Scott has a better shot to make the squad. Same with Keuchel vs. Folty or Velasquez or Houser (all of whom I like).
Because he was a 14th round pick, there's a notion that Scott is a sleeper. Let's wake up, wipe that notion away, and realize he's just as good if not a better prospect than our three 1st rounders from 2010 (okay, a bit rhetorical here).