With regards to your 2nd point, real life is littered with examples of lower rated (or non-rated) recruits that ended up in the NBA, or clearly could have contributed at high level D1, if only those high level teams had taken a closer look. Jeremy Lin, for a very recent example.
Or how about Sherman Douglas, back in the mid-1980's at Syracuse (for those old enough to remember). The guy had one scholarship offer from a D1 program... Old Dominion. Syracuse thought they had Boo Harvey locked up as a PG recruit, but that fell through due to academic concerns. So what did Syracuse do? They effectively poached Douglas from ODU at the very last minute, and the guy ended up the NCAA's all-time assist leader when he graduated, and played many years in the NBA. Obviously, an awful lot of high-level D1 programs missed on Douglas, but they certainly could have used him, if they had known.
It's just like the situation you've described. So yes, it does happen in real life. Looking for diamonds in the rough is part of the fun of the game, IMO.