Placements don't mean much of anything past, "This is where you're starting your climb from." Its a starting point, nothing more.
For example, I ended last season Silver 2, dropped to bronze 1. Completely crushed Bronze in 10 games, moved up to silver 5. Met some resistance due to the mixed bag nature that is Silver 5 at the present point, 15ish games later, I'm silver 4. Currently, I've more or less crushed though silver 4 and I'm sitting at the beginning of promos for silver 3.
Using LoLking as a base, my ELO before placements were 1360.
After, 1102.
Currently, 1270.
So, i'm almost 200 points higher from where the system started me from.
Your deserved ranking is where you end up when you're at a consistent ~50% win rate, those losses where someone else intentionally screws you over, will be made up eventually. If you keep getting "feeders" consistently, maybe you should take a good look at yourself first before anybody else.
TLDR: You want your "accurate measurement level of skill"?
Continually play the ladder.
Git gud.