Placements don't matter so don't sweat em. You have a hidden match making rating (MMR) and even if you go 10-0 or 0-10 the game will give you the proper SR for each win or loss after your placements until your MMR and SR are close to equal. So you'll see some people getting like 50 sr per win and some people getting 5 sr. If you're getting high SR than you're better than your competitive ranking and the game is catching you up. If you're getting low SR than you're probably worse than your competitive rating.
If you really wanna get a rating you don't deserve then make a new account and level it up to 25 only playing Arcade because quick play is too unpredictable. Then in competitive main an off meta character that you're really good with (sombra, torb, symm, junkrat etc.) and the game compares your stats to other people playing that character and since it's off meta you have less competition. There was a top 500 Sombra one trick(meaning they only played that character) last season with a 44% win rate but because they were way better than most Sombras they would get more SR for wins and less SR for losses. I think it's dumb as fukk but that's why you see so many high ranked people playing stupid fukking characters.
If you really wanna get a rating you don't deserve then make a new account and level it up to 25 only playing Arcade because quick play is too unpredictable. Then in competitive main an off meta character that you're really good with (sombra, torb, symm, junkrat etc.) and the game compares your stats to other people playing that character and since it's off meta you have less competition. There was a top 500 Sombra one trick(meaning they only played that character) last season with a 44% win rate but because they were way better than most Sombras they would get more SR for wins and less SR for losses. I think it's dumb as fukk but that's why you see so many high ranked people playing stupid fukking characters.