I funny but sad phenomena I've noticed during my recent losses.. (may help you climb)
when your MMR drops you get these people on your team. They are really shit players ad just get steamrolled and there's nothing you can do about it so you don't do anything about it and you end up winning by doing something else really really hard.
But when you boost your MMR you run into people who are slightly less shitty and you get a chance to help them.. but you shouldn't, its a trap. They are now skilled enough to know to tell you that they need something and what they need. They are smart and experienced enough to set it up for you to come help out. But its bait! Sometimes you help and get kills but it still wont feel worth it for a long while.
I wonder how many people lose easy games because of this. I find myself doing really well at first then things just go south as soon as I try to help the team. But then when I ignore the team I prevent those really annoying easily avoidable things that happen sometimes. Not every game but las time I reached this point I could predict that I'd start winning again by playing like an asshole and pretty much disregarding my team at times lol
hope this helps someone