Your rank is decided on your W/L Ratio. Naturally, the more games you win, the higher win rate you have and this pushes you up through the ranks. As far as we have been told, its mostly on the W/L ratio and little to do with performance and or stats.
However IMO, to climb out of lower ranks relies on improving a few things:
Positioning - Know where to optimally position on all the maps with a given hero and where and when to rotate is crucial. When you die, ask yourself why you died, where were you standing, why are you standing there and what was your plan? You will die in fights, it happens. Im not talking about team kills or simply catching a HS from a hanzo. Pay attention to where you are and why you are there.
Game Sense - Simply knowing that a Genji might have blade the next fight, or Rein having hammer allows you to make better decisions on where, what and how you will play in anticipation of the enemies Ultimate plays. In low ELO/Rank there really isnt much coordination with ults so tracking them is as easy as paying attention to when the last time you seen the enemy use their ults, how they behave when they have them or how far along your own team is on theirs.
Counter picking. - If you are support and know that the enemy is running phara mercy, then playing a support hero who isn’t good at range/hitscan against Phara may cost you games. Always be willing to play a wide variety of heros so that you can make swaps if your team isn’t willing to. You’ll be surprised on how much a hero swap can change the outcome of team fights and you don’t have to be GOD TIER either. Obviously don’t play heros you have no clue how they work. Do that in QP.
Avoid soft throwing - Specifically taking High risk low reward plays. This might sound strange since we all see pro and higher elo players make crazy plays but i have seen may lower elo games where players just mindlessly make risky plays that mostly end in losing the team fight. On the off chance it works, cool
. But don’t think its a literal strategy to win. Just keep in mind how much risk you are taking in a fight and mitigate or offset it by responding to it appropriately.
Don’t rely on your teammates all the time - Support players are notorious for assuming that DPS will peel for them and that the other healer will back them up. While that becomes more common in higher ranks, its not common in low rank. Just dont assume your teamates are going to do anything but press button in hope they get POTG. Take matters into your own hands, this comes down to practice and taking the 1v1 flanks on tracer, genji, sombra etc. In low elo i see supports get harassed by a tracers or sombras, ignore them and assume that theres nothing they can do and that their the DPS is going to do something. Start fighting back. Even mercy can 1v1 in these situation if you are caught out. DOnt just stand there. I have fought off tracers and sombras as a mercy many times. The funny part about this in low elo is that the they dont expect you to put up a fight and most might panic, back off or at best you can secure a pick. Trust me, no one wants to get out played by a support player as DPS.
Stop pressing Q when others do (Unless its a coordinated attempt). This is a bad habit in low ELO. Most players panic and all press Q (Ult) at the same time because they hear everyone else doing it. STOP. If your team is using anymore than 2 ults in 1 fight, your most likely wasting one of them. Dont waste your ult.
Stop holding your ult - I know i just said to stop pressing Q all the time. But also, dont hold your ult for too long. There are a few heros in the game, that can hold thier ult for a bit for the right time, but if you know your ult counters the enemy team in making a play, then go for it. It will happen that sometimes you throw your ult. It happens at high ELO too, but be mindful of how long you have it for and learn from the mistakes.
Review Replays - Doing this allows you to see where you could have done better. After a loss on a game you think you should have won, take a peak at the replay and try to spot mistakes you make as well as potential opportunities you missed to make a team fight sway in your favor.
These are just some of the things to look into. Each Rank has its own set of skills you will need to improve on as you rise through them. So dont think what works in Silver will work in Plat and what works in Gold will work in Diamond etc. As you get higher in rank, so do all the other players skills so you will need to sharpen your own skills again as well.