Everyone here agrees that the most annoying thing you can have in a game is AFK's, ragequiters and trolls, just that the MM can not predict, has no way of knowing if someone is going to be a troll or not, this part we have to leave to the tribunal. What everyone also complains is playing with players who have no idea what they are doing, the only way I found to know if someone is experienced or not is the number of games played, so I thought a formula that calculates a "true elo" that would be used by MM:
true elo = [(total games) x (won +1)] / [(leaves +1) x (loss + 1)] x Elo
The more matches you play you'll be more experienced and his "true elo" will be higher, also note that if you leave a game you will be heavily penalized and your "true elo" is halved in the first leave, this leave leavers together.
I put a friend of mine as an example, he has 142 games with 75 wins and 67 losses, and his Elo is 1257: His "true elo" would be [(142 x 76) / 68] x 1257 = 199.493 and when the MM was look for a teammate and opponents they would have their "true elo" near that number.
I put my friend as an example because I have another friend with 2 wins, that's right only two victories, and he has 1315 Elo. Putting in the formula: 2 x 3 x 1325 = 7.890 realizes how vast is the difference? He even jokes that does not know how he won both matches and said he will never play ranked again to not lose the Elo lol.
I have 1727 games in normal mode and started playing ranked this season, with this amount of games I can say I know how to last hit, I know about putting wards in important spots, these things of the game that seems simple but it seems that few people knows. A little story just to illustrate what I mean: Before yesterday I was in a game, win a fight in bot lane I was with half HP I went to dragon called my teammates (I wrote in the chat that I needed help several times and ping) so they were all running to gank top, in short, I could not kill the dragon alone had to run and the top player escaped.
Another thing I noticed is that the ELO system of the LOL is not the same one used for chess, in chess that the higher your ELO more ELO you lose if you lose to a less experienced player. Let me give an example: Last week I was playing with my 1257 friend in duo queue, I had 750 ELO in the day, first game we won, he and I won 6 ELO, until there normal I was playing with someone with more ELO than me. Second game we lost, I was thinking "Omg he will lose like 50 ELO" we both lost eight ELO, yes only 8, this is less than a queue dodge. Want people to stop complaining about the duo implement the REAL ELO CHESS. It would be like: OK 1700 sir you want to help your 900 friend get ELO fine, if you win (you have to win) you get 5 ELO, if you lose you lose 100 or more. The people will think twice before the duo, then they're going to call his friend and say: Ok dude let's play a normal and see how you play, do you play suport or tank or jungler? let me explain some things about the game ...
I really hope that MM is improved because I got tired of playing with people who do not have any notion of game strategy and think only of killing, leaves the base fall to chase players, not to mention leavers, trolls ...