Forgiveness
Whether I am on the winning or losing team fighting a 4v5 or any match up where the amount of players isn't balanced simply isn't fun. Not only is the game itself not fun but so are the things that come after the game. Honestly it is very unfair when you lose just as much LP (or gain) when you are basically at a guaranteed loss. Also there should be more of a reward for winning a 4v5 and vice versa, more of a penalty for losing a 5v4. The main complaint to posts like these is that "it will always be abused" but if you think about it certain restrictions can be made in order to prevent abusing. For example make it so you lose LP if you go AFK (similarly to if you dodge in champ select) and like make a timer to where you're only counted "AFK" if it has been a certain time. Also making the penalties for going AFK more harsh like if you go AFK two or three times you're banned for (insert time here). Basically what I am trying to say is that a lot more Good will come from having forgiveness in the ranking system than Bad. Honsetly it would probably give people the rank they deserve not the one they are forced to have by unfortunate match-ups.