"When it comes to who stays and who goes after training camp, he absolutely does make that decision." - there's a difference between a roster and a line-up. As far as I know, the GM decides the roster, and the coach decides the lineup. The roster is usually involves around 3 extra players. (i.e. the lineup will be 20 players, while the roster might be 23-24) As far as I'm aware, the coach does not decide the roster, as that's the job of the GM.