One of the challenges NBA scouts and executives face when evaluating draftees is that, for the most part, pro and college basketball are two different games played similarly. Much of the college game is lost in the pros. So players who have difficulty in some aspects of the NCAA game can quickly blossom in the NBA because those particular aspects no longer matter as much.
Similarly, players who excel at one aspect in college often are forced to change their style and, as a result, they bring new talents to the table that were not needed previously. The same thing can happen with players who come over from Europe, as that game can be viewed as similar to college, only with much better players.