I've been really trying to get better lately, I only play support and only lich I've gone from from 10 mmr to 190 mmr and I hope I can end with with around 1500 MMR (slightly more when I calibrated many years ago) and I'm stuck cause I got punished for playing too well too early, the forced 50% winrate gave me a 6 win streak and now its a gamble I win or lose and that's according to Valve's algorithm.
No matter what you do, you will be punished and rewarded by the 50 percent thing, look at this chart, you may see I only have 9 loses and 10 wins, but I abandoned a game but my team somehow turned it around somehow, so its actually 10 loses and 10 wins, I won a game after 3 loses, and I doesn't matter what I do cause I either will won 2 more games and then go for a 10 losing streak and go win another 10 games and end up at 190mmr cause shit doesn't matter.
So either I have to hire a booster who can break the algorithm jail, get a coach (fucking pointless) or give up cause I can't improve cause the algorithm will always block my progress and I guess that's intended.
Source: https://www.reddit.com/r/DotA2/comments/pzcu5b/i_dont_care_what_any_lazy_valve_employee_says/