Good advice. Junior High School years mean diddly in the big picture. At 13U, my son pitched a total of 30 innings last year, and that includes scrimmages. He ended up the year as the 12th man on an elevan man team. The most wastefull, pathetic year imaginable.
Eight months later, as a freshman this year, he's competing on the JV team with kids who throw upper 70's to mid-80's. These kids were all #1's for their team. They've pitched a lot of innings and have all had arm injuries. Power, but wild and no control of their emotions. What the coaches are looking for is can the kid get outs, and handle the mental part of the game. During the early spring practice, my son has risen from the #5, to the #4, to the #3 and is already pushing the #1 kid to be the team ace.
In the coaches eye, it doesn't matter that he only pitched 30 innings the previouos year, or sat the bench and watched his team pathetically lose game after game; he's being graded on what he does now.
I should add, the High School coaches are too busy to see any JH games. They haven't a clue of what the kids can do until they see them in practice.
I recommend getting him started on Dorfman's books about the Mental Game of Baseball and the Mental ABC's of Pitching. (I forget the exact name of the books, but look up Dorfman. You won't be disappointed.)