Advice for climbing out of Crusader?

Almost 5000 hours in Dota, but I never played ranked, because I find it too stressful. On top of that, the one time I did play ranked calibration games, they all went awful. I think two games had a leaver and a couple were peple running down mid.

Either way, I ended up in Guardian 4 and climbed to Ceusader 2, bur quickly got demoted to Crusader 1. I had 9 loses and 1 win, and that one win was a stomp…

Almost every match, I had very new players who were still learning the game or straight up trolls, who picked pos 5 Sniper or feed mid because they didn't want to play that role. Keep in mine, my behaviour score is 10k, lowest it's ever been is around 8500.

So I mainly play Support roles – Shadow Shaman, Warlock, Earth Shaker if I think the laning phase will be somewhat peachful. But I was thinking, maybe I should switch my role or pick better heroes?
I usually win my lane or at least get my carry stacks in triangle or jungle and somehow, they always fall behind. My item builds are pretty decent, making sure I can take care of my carry or to get my Auras as a pos 4. I also watched a lot of videos on roles jobs, general gameplay, etc. I also watch Dota 2 streams a lot and I'm generally familiar with the flow of the game and all the heroes.

Nevertheless, all this work and trying to improve is not working out. I feel powerless to help a team, that more often than not, does not want to win or improve. I feel like I'm playing with angry and stubborn babymen.

So, what do I do? How can I improve enough to acrually win games like this? I know my luck in matchmaking is not going to get any better, but at least my skill can improve. Should I change role or heroes I play? Any meta hero/build worth abusing? Literally willing to do anything to escape this hell… I know I'n better than this.

Thanks for all the answers and advice.

TL;DR; Unlucky matchmaking caused a big lose streak and crap calibration games. Stuck in a low rank and I wanna improve/learn to solo carry babymen. Neeed advice and help, thanks!