One of the things my sons' high school coaches have said in our parent meetings is that they have a couple of days (and in Nebraska those are in a gym) to size up the talent of the players trying out. They will probably get it wrong sometimes. If he plays another sport and it's a new coach then he really only did have a couple of days. If he is anything like our coaches he will continue evaluating during the season and make adjustments where needed. And as others have said, if he's already gotten the attention of college coaches it really won't matter anyway.