When guys play for these kinds of teams, whether it's a national team or a conference "all star" team touring overseas, the team's head coach asks the college head coach what the player should be working on. The players hear the same things from their college coaches day after day. They take some of what they hear to heart and work to improve it; but whether because of perceived overload, stubbornness, or some other reason, they tune out some of the messages.
It can help a lot to have a coach like McKillop look at a player's game and reinforce the critique he hears back on campus. Whatever new/different coaching Grant gets from McKillop will help his game (and Atkins' game from the week he spent in tryouts), but the reinforcement of Brey's agenda for the player will help just as much.