I pretty much only play blind or dominion. :s
I still maintain a < 1 win rate in ranked whenever I do it. Pretty easy to hit 1400 regardless of circumstances. Every bad player you get will get counter-balanced by a bad player on the other team at one point or another. Because of that, average players will stick around 1200 elo, below average will go below it, and above average will go above it. There's a general fluctuation range of somewhere around 100-200 elo, but that just means if you're an average player you'll be somewhere from 1000 to 1400 every season pretty much. So no matter what, so long as you're average, you should be able to hit 1400 every season.
So quite honestly, it takes a certain level of... skill, for lack of a better euphemism... to not be able to maintain 1200 elo. Even a below average player who deserves 1000 elo should still be able to hit 1200 elo at some point.