one more observation, some kids who just played together "forever" in youth, summer & hs just are out of their comfort zone with new/strange personnel around them
our hs coach was a big proponent of keeping his players (and expected future players) together, and went to great lengths to do so - in summer, fall, and even youth leagues - his thoughts being they will know each other so well they would anticipate each others actions
there was real grief when about 6-8 players near my sons age (pre hs) abandoned local teams and played on whatever the best travel team they could make
his attitude quickly changed when they arrived in hs - and these 8 kids who were all friends but had not played together, looked "light years" ahead of upperclassmen in their first week of practice - plays & situations had become instinct
he don't worry so much now