The original star rating that a player has when he hasn't been scouted at all is completely random, so don't look at that. When you do scout a player, potential is more important than the new star rating they have. Grade rating is also less important than potential, but that should still factor in to the way you draft. The box scores should be ignored, they have very little impact on how good the player is.
In my opinion, you should find out the potentials of some more players, and pick the one with the highest potential. For more advice on how you should rank your players, you can just reveal the star rating, potential, and grade rating of the players you scouted right here and I'll do my best to give you rankings.