Interesting study. 68% seems like it would be difficult to maintain, but like a lot of good baseball studies, it gives numbers to ideas that we suspected anyway.
One thought that came to me after reading this is that when speed is the primary tool of young players, they seem to get their opportunity a little earlier (and perhaps before they are as ready as the other prospects). Maybe just a secondary factor (maybe no factor at all), but iit appear to me that if speed is a big part of your game, the Twins are getting you your opportunity earlier that otherwise justified.
Revere would fall into that category. Of the 3 fast trackers, he clearly doesn't feel like Mauer or Morneau, who were not only in the majors fast, but before too long picking up MVP support. Even though he doesn't figure into draft analysis, Carlos Gomez also seemed to be in the majors because his speed was there, but the rest of his game was behind the others early in their MLB careers. Speed is usually the first tool to depreciate, which would not only justify earlier first looks, but less concern over length of the contracts for this type of player. I maybe way off base on this, but just saying the study was provoking some other thoughts.
The other extreme (not to beat this idea too far into the dirt) seems to apply to Morales and Plouffe. Speed is really of no significance to their career. So if the talent arrives later, its easiier to wait on them.