possession bar and injuries/sending off

as many here will know from watching animation of your matches you will often see the possession leap to either one side or the other whenever you have injury or sendings off,my question is why does it take so long for AI to decide? almost a full 20 mins of animation game time sometimes elapse before you either have injury or sending off as this time can and is important countless times goals have been scored against me in that time,if you add the slowness of putting subs on or changing formation games are lost, but on the other hand a non present manager has their subs on almost straight away and in many occasions when they have player sent off become almost unbeatable