I typically don't even consider anyone less than star potential, and anything under perennial Allstar isn't going to be worthwhile in higher divisions. Aim for 5/5 balls in skills/potential, next preferential being 4/5 and then either 3/5 or 5/4, depending. 3/5 can be decent, and either way can be sold for a lot of money because people go crazy for MVP, HOF and ATG potential.