If the Rebbe told the soccer story to a certain Bocher who can easier learn (and the Rebbe knew that) That is one thing, however this story was told to everyone. Some of whom can learn 12 hours and some of whom can only learn 6 hours a day. The point of the Bein Hazamin story was these boys needed a break and to compare a bunch of bocherim who went to a game Bein Hazamin to a bocher who smoked and did drugs at the yeshiva during the zman is not the same. Clearly it is not an averiah according to many major poskim (Like Rav Moshe Feinstein)
A Rebbe is supposed to know each Bocher and whats is appropriate for him, Not what is good for the Yeshiva and its “reputation”