You have to do whatever it takes to stop you from tilting. Tilting means you’re going to lose, period. Once you notice that you’re tilting, you either need to stop yourself, take a break after that game, or go back to arcade/QP until your mind is clear. Whatever it takes. Also, remember you cannot win every game. That’s just a fact. 1/3rd of your games will be unwinnable. You can maybe make it close if you make the right decisions, but it’s doubtful you’ll win. These games include anything from 5 bad teammates against 5 smurfs, leavers, throwers, etc. Its out of your hands. You’ll naturally make mistakes, but some games are just not possible to swing. Accept that and don’t let it bother you. Just play as well as you can given the circumstances. Once you let that game tilt you, you’re now tilted for future games too, and you’ll lose even more.
As for the other games, there will be specific reasons you’re losing that don’t just involve teammate failures. You’re likely making the same mistakes and not noticing, especially when tilted. Its very easy to get tunnel vision in this game, and you can’t let that happen. Think on a macro scale of how you can swing each teamfight. What’s your objective? If you’re a sombra, which healthpack provides the most value to hack? Where should you place your translocater to remain in teamfights as long as possible? Are you trying to get ult charge, stall the payload, or secure a kill on their backline? This stuff matters. Not every objective is just ‘kill something,’ and not every target is created equal. Even if your team has a man advantage, which hero is dead on your team, and which are dead on the enemy’s team? If your tanks are both dead, but your enemy has their shield tank, a healer, and a bastion on point, should you take that fight? Think about the bigger picture beyond just killing everyone, since simple man advantage doesn’t necessarily mean you’ll automatically win.
Most importantly, think about how you can enable your teammates to do better than they already have. If your comp is a mess, how can you improve it? If the enemy comp counters your pick, what can you do to swing that to your advantage? Whose the problem player(s) on the enemy team, and how can you nullify their effectiveness? Would it help if you give callouts, even if nobody else is talking on voice chat? Would it help if you track enemy ults? Would it help if you keep an eye on the kill feed and tell your team when to push and when to wait? It’s all relative.
Everyone says to focus only on you, and that’s true, but you can also focus on the bigger picture with enough awareness. You can’t force your teammates to do things differently, provided they don’t want the help, but you can swap heroes, counter the enemy, wait to nullify an upcoming enemy ult, keep an eye out for flankers, secure key picks, help focus down whoever your teammates are tunneled on for a final blow, etc. Realize that you cant win them all and accept that, but also try to look at the game as a puzzle consisting of what you can do to change the outcome. You’ll be able to see your mistakes even in an unwinnable game and will grow from it. Do that enough over time and you’ll grow as a player until every game in your rank becomes easier, and you’ll rank up.
Oh, and remember, the comp ladder is a grind. There’s nothing quick about it. Even pros doing ‘X to GM’ runs have to play a lot of games to rank up, and they already started with the game sense, knowledge, and skill that you are still learning. Don’t give up. Keep playing, forget about your SR, and grow as a player. Its not a quick path, especially when you’re not already the best of the best, but you can learn and grow to slowly get there. It takes time and lots of dedication, and I think that’s what demoralizes people the most. Even the pros learned how to be so good by playing previous fps games. None that I know of started from square one, so they too had to take the same path we all do, albiet maybe they did it in a past game. Even still, pros always learn new things too, hence the reason every OWL team has multiple coaches. Nobody knows everything.