happens with prospects from there all the time, miguel tejada was playing in america for more than 8 years before he came out and admitted to lying about his age and name. Im sure there are people in the bigs who are stars that use a fake name or age.. not a real big deal since its become so common place
Studies by Bill James of the statistics of position players show that most peak at the age of 27. (This was in the pre-steroid era.) The peak five years tends to be 25 to 29 or 26 to 30. Teams use projections of a player's talent and development at a certain age to guess how good he will be in the future.
The point is obvious, a certain level of talent in a 20-year-old might make him a very good prospect but would tag a 16-year-old as a future hall-of-fame prospect. They seriously overpaid for his services based on a false age.