I know normal, Dominion, and the ranked modes all use an MMR rating to pair you up with equally skilled opponents. Is that the case for the new Howling Abyss map?
I know we have separate MMRs per map. I believe HA will have a new hidden MMR specifically for it but we get that ARAM is less about precise skill matchmaking and more about SUPER RANDOM CHAOS. So the focus is on light balance and more on getting you matches in the queue faster.
It'll have its own hidden normal Elo, but be based on your SR normal Elo initially.
The answer is yes. I played a game as an experience player and watch my team peel for for the adc or apc and when I watched a game of a lower aram game they just do whatever they want. Although there are cases that you get paired with someone not of your MMR. I had an anivia who keeps blaming team mates while she is 4-15.