i was from 3.8k drop till 2.9k...
and now finally i slowly climb back from 2.9k to 3.4k... =.=
it's possible for climbing in solo....
just make sure you're the mid player and keep ganking the whole damn game.

and party ranked match... 3.7k drop till 3.3k... cause always teamup as 2 person and join the team mmr...
no luck trying.

Im a 4.6k MMR solo player and climbing
To get your mmr high or i can say, not dropping drastically, if your mmr is at 4.1k+ you should nt be worry about the carry or the mid player. You should worry more on the support role, at 4.1k mmr, everyone wants to become the mid and carry player, to win a game, sacrifice your mid and carry and just go for support if you think your support role is also actually good.

Of cause they might blame you on the lose game (Support roles always get the blame), but a real mature gamer will not blame you. just do your best supporting the lanes .

even at 4.6k MMR i still get stupid teammates that feeds on their lane, flame, complaint etc,
but just ignore that lane if you see he is on a lane with a not so strong late game.
Support your late game if this circumstences happen.

To be able to secure a win game in Solo mmr, Support must know the placement of wards, smokes, ganks, because when coming to ganking, supporter roles are the leader in this specialised ganking. Therefore call for gank if needed , ward if needed , smoke ganks if winning wars to secure your win and not throwing them, and Happy Dota gaming !