2 days, I've played 5 games, in those 5 games, 4 of them had 1 afk eigher in my team or the enemy team... I've to start this discution because it's not even funny playing like this, or the game becames impossible to win or to easy to win... Riot should invest more time in balancing this... because this is core of the game, without full 5x5 a game loses it's porpuse... While I believe it's not easy to come up with a solution to deal with this, I believe there can be a solution.... like 4 games, almost in a row... I'm fealing trolled by the game (not the players).
If no solution can be implemented at least half the LP for everyone (except AFK player) or cut LP based on the time the AFK player is AFK... here's a base formula for this... pure math, and I'm sure it can be improved with some more variables if Riot puts the effort in this
( afkLP = normalLP - time * someFactor )
Examples ( lets assume a factor of 0.6 ):
I win 25LP in a normal game... someone AFK for 20m of the game... so I would win 25 - 20 x 0.6 = 13Lp
I lost 17LP in a normal game... someone AFK for 20m of the game... so I would lose 17 - 20 x 0.6 = 5Lp
I mean it's fair as the game loses it's porpuse that the winning team wins less LP for the very easy game and the losing team loses less LP for the unfair game... and it will also encourage the team with the AFK to play a bit more to stall as much as possible and the team with the easy win to try and close the game as fast as possible to try win as much LP as possible (at least it could give some meaning to a 4x5 game :D )
Edit- forgot to mention, if for any reason the team with the afk player for some "miracle" wins (a small % of cases but still possible) then use normal LP win/loss as a reward