My oldest son went to a MLSB tryout when he was 16. He met a catcher from the school that he wanted to go to (and eventually signed with). The player told him basically the same thing. The coaches were all nice during the recruiting period and they changed dramatically when practice started.
I told him that it's just like the military, They are nice and tell you all the good things about signing up then bam!! boot camps starts.
The coaches are there to win games and to help your kid get an education.
A lot of guys had fun during boot camp including myself. It's the same in the police academy. It's what he wants to make of it.