You simply couldn't necessarily translate a big or a poor night in a game to his overall level. Ball skills and box scores are just a first look, as happen during other BB's games where sometimes your best player will play an anonymous game or an average one will explode for a big performance. Ball skills are well connected with the salary of the player, however a player earning 3,5k isn't necessarily better than someone earning 2,8k.
Of course you could make suggestions. Maybe he could be a valuable defender first of all.
But it's hard to put too much faith in boxscore. If you're really high on drafting, discovering at least some skills with proper trainings could be useful to have some certainties.