This is a bug bear of mine too, why is it that computer auto-subs are so fast in comparison? It'd be great if there was an auto setting within the game that added a 15 second break for a manager (if present/watching the game) to actually make the sub when a player is injured. Same way some time is set aside when picking penalty takers in knockout. 10 minutes is far far too long in the real game if a player is injured and completely unrealistic. Needs to be changed.