The referee asks hockey players to switch players during a face off. Why?
Because the ref has seen one or the other encroaching (illegally) and he doesn’t trust the players to not do it again.
The ref is suppose to have clean ice to drop the puck, and if one of the players is encroaching on the clean ice, he can ask them to move.
Basically the player(s) are misbehaving.
Even the Canadian players…??