Risk versus reward. That's the balance teams attempt to get right as they compile their draft classes each year. Does this player's upside, ability and production outweigh any issues he may have off the field and weaknesses he has on it?
The teams that best answer those questions are the teams that consistently draft well. It's no exact science, however, and there will be huge misses from teams every year, which of course is what makes the draft so much fun. Everyone loves tracking the players who were deemed big risks but who had huge potential coming out of college.