A way to make AFK's not affect people as much

If someone jsut suddently leaves a game you were winning, its pretty annoying. How about if they were afk for at least 15 minutes, all of the playing people will take 50% reduced lp loss. The one who afk'd will take 50% increased lp loss. This will discourage people from leaving a game they are losing so that their team can get reduced lp loss.