I can see were both of you are coming from. Maybe from a D.I standpoint, all three trainees blow but from a D.V view, the first two are great. They both only have 1 horrible guard skill a piece, which can easily be fixed with training. Give them 2 full seasons worth of training and those two guards will be starting for you.
Definitely sell the SS potential guy. I really don't think 500K is a realistic number though. Maybe if his stats were amazing, but lets face it, they're not.