Also please be wary of judging too much on total overall ratings. As you get experience, you will find that a catcher with an overall rating of 72 is probably more valuable than a SS with an overall rating of 79 or 80. This is because all ratings are factored into the overall rating while range, and to a lesser extent glove, are just not important to a catcher's ability. Similarly a good hitting 1B is going to have lower overall ratings than a good SS or CF.
For pitchers,in my opinion, the most important ratings are control, splits (vs LH & RH batters) and 2 or 3 good pitch ratings. Pitchers have between 1 and 5 pitch ratings for up to 5 different pitches they have mastered. For starters, there should be at least 2 and preferaby 3 good pitches (65 plus as a minimum and over 70 preferably). Relievers can get by with 1 or 2good pitch ratings. Velocity, while a plus, is not critical.
For hitters, the 5 most significant ratings are contact, batting eye, power, and LH/RH splits. Speed is a plus.
For 19 & 20 year olds you may see overall ratings for current and projected as disparate as 59/88, i.e current rating of 59 and projected of 88. Whether they reach the projected rating is dependent on many factors, but in my experience few reach the full projection but quite a few come reasonably close. The dollars spent on scouting will heavily influence the accuracy of your projected ratings. There are separate scouting budgets for advance scouting (affects the accuracy of seeing projections for other teams prospects when considering trades, among other things), international scouting (international free agents), domestic high school scouting and domestic college scouting.