That's just silly. There's hits and misses from every high school, every college, every country and every continent in the world. Of course some deserve to go top-5. Maybe not as many have been drafted there, but you can say the same thing for the prep-to-pros, the one-n-dones, the two-n-throughs, and any other college player regardless of school, skills or position.
I mean, I agree that most foreign players aren't ready to star right away when they come over here, and thus choosing them higher up in the draft is a big risk, but, again, that can be said for most of the players drafted any given year anymore.