I want to share something some might not know, i might be wrong & i know it might offend some but after a lot of experience i think i am mostly correct.
Players with same rating,ELO can unfortunately have a big difference in their carry power depending on their class,champs.
Forexample: 2 teams with 4 1500 ELO players, they both have 1 2500 ELO carry but one player is a Heal Bot Jenos or Damba main while other team has a Bombking or Shalin main. I would bet that the damage main will be able to carry bad teams much better than the healers & win maybe even 70% of the time in those cases. I have seen it happen far too many times & if i want to win i would have a damage,FLank main carry on my team anyday over a Tank,Support main sad but true.
Its an even bigger issue with Tank mains, i am not saying that they have less skill or anything but their ability to carry worse team mates is unfortunately low. I have seen high ELO 2700+ high winrate 60%+ Nando,Torvald mains being quite hopeless with lower ELO team mates, almost to the point they were barely better than a 2K damage FLank main.
At any given ELO there are the bad boosted,lucky players who clearly dont belong there, there are average players & there are also the very good players. All will have different impact on matches,there is a very big difference between a 1 KDA 2.5K ELO Andro main vs a 2 KDA plus Andro with the same ELO, the low KDA player very likely only knows how to play aggressively & relies on his good aim too much which may not work in a given match while the high KDA player very likely knows how to slow down & position properly to not feed the enemy team.
There is also this issue of Matchamaker overestimating a high ELO player's carry power.
ForExample:
Team A ELO--------Team B ELO
1. 2000---------------2400
2. 2000---------------2400
3. 2000---------------2400
4. 2000---------------2400
5. 4000---------------2400
Both teams have an average ELO of 2400 but most of team B is a lot better than team A, its a bad match up & very hard for that very high ELO player to carry. I had a similar match with a 4K pip player on my team no offense to him but he really couldnt do much,again there comes back this issue of vastly different carry power between champs, if he was a Andro or Kinessa main no doubt he would have carried much better & we might have won. SOLO carry works below 2K but after that it becomes much harder where even the best players can struggle, so maybe after 2K the MM should stop considering the average ELO's & never create matches where most of team 1 is better than most of team 2.