As to the original question of High BBall IQ players who have not made it, this is hard. I'm 32, so it gets hard once you get back a few years, because looking at drafts at some point I'm only familiar with players who "made it," and have no idea why all the other players who didn't make it were drafted in the first place (whether for shooting, IQ, defense, athleticism, size, etc).
There are innumerable college players with high IQ who everyone knows lack the skill/athleticism/size to play in the NBA so we never even hear of them leading up to the draft. So we are talking about a funny group of players who were good enough overall with size, athleticism, etc to be worthy of being drafted/signed but were also well known for their IQ who then flamed out.
After a quick look, (wikipedia for draft lists, google/draftexpress for profile), here's a brief list:
Johnny Flynn
Wayne Ellington
Julian Wright
Nick Fazekas
Adam Morrison
Shelden Williams
Marcus Williams (UConn PG)
Ronnie Brewer
David Noel
Chris Duhon
Dan Dickau
To name a few.