A couple of names associated with the Raptors made this list...
Fear Factor: 4
Super-athletic foreign big comes out of nowhere, ramps up a ton of hype, then goes to workouts and .... wah-wah. Biyombo has talked about leading the league in blocks and rebounds. Bravado is excellent. But it can also belie an effort to gain a foothold on something other than ability. Biyombo brings great length and athleticism but no polish or offensive repertoire. So he's kind of the anti-Jimmer. But players in Biyombo's mold can either be a revelation or a colossal bust. Just for comparison's sake, the last player similar to Biyombo in terms of physical nature was Thabeet.
Good luck with that.
Fear Factor: 3
Similar concerns as Fredette, only magically shorter.
When Walker measured in at 6-1 vs. the 5-11 many scouts had him pegged at, the phrase "See, he's not short at all!" was used. This despite the fact that he's still short, he just plays and seems shorter than he actually is. Walker has a tremendous scoring ability, but defensively there are going to be questions. There have been plenty of players of diminutive stature to make it in the NBA and even become borderline stars. But few of them have been drafted at Walker's projected position or with his expectations. Walker was the college player of the year for a reason. He was also kept out of the top ten for most of the year until the talent stampeded out at the end.