By the time you reach level 25 the matchmaker has a good idea where you belong if you play the way you always do. I tested this out long ago back in like season 4 and 5. Being on PS4 I can make as many accounts as I want.
So I set up 5 accounts. One to play just like I always do, one for each role only so a tank account, healer and DPS. Then the fifth one I tried to play terrible. Heroes I never touch, wiffing widow shots on purpose.
When I did the placements on them, the first four were all placed between low diamond to high diamond, back when I use to play much more and just better. The fifth, I was able to get placed in high silver.
So I played that one a bit more to see how the Sr gains worked. Play a game like normal, gain almost 40 sr, play like crap and lose, lost 30 Sr. If you keep mixing it up, sooner or later the system just assumed you belong there and the gains and loses just equaled out to about 25 either way.
So yes a Smurf can do that if they put time in. Now before people attack me, I have not touched that account or any of the alt accounts since like season 6.
So yes you can mess with the match making before you even reach level 25 to give you what you want. That’s not even counting people that might just use FFA to level up.
Why do you think pro level players and top 500 are able to start so low? Because they don’t try at all when leveling so when they do placements they don’t try and get bronze then do their bronze to GM thing.
The matchmaker should already have a good idea where you belong by the time you hit level 10