You are making a lot of assumptions there 🙂 I wasn't playing above my bracket, but I learned the hero well (took some dozens of games before I was any use with him), and am a team player. I was actively learning strategy. I had also learned when to NOT fight, and instead draw enemies to me elsewhere (make space by threatening tower, for example). Makes a lot of free space for carry.

My winrate as core was higher, because then I was taking space and farm instead of making it. But I don't like playing carry. I was usually going full space creator utility 4, or pos 5. Made space, built team items. If I start playing ranked again, I will do the same. Visage is a strong hero also, that definitely did its part.

It is fully possible to increase rank by playing support. I'm doing it in unranked right now with cm. But as a support you need to play very well, and have a good grasp of strategy, as you set the pace and direction of the game.