Skill isn't a stagnant measure though. The game is matching you against higher opponents, because it thinks you can compete with them at some level. It's saying that your skill is good enough to bump you up to Diamond. Your rampant quitting is only making things worse because your hidden skill is saying "you can play diamonds or higher and be competitive" but your quits are saying "we can't reward the improved skill because of terrible behavior."
I decided to delve into your stats and see what happened in your placements to make you seem like you are so sure that your rank is Platinum.
Code:
Game # Result K A D [(opp. rank when matched opp. final rank)(opp2)...]
------------------------------------------------------------------------------------------------------------------------
Game 1 W50-27 9k 6a 7d [(ur G) (ur P) (ur G) (ur B)]
Game 2 W50-31 12k 6a 10d [(ur P) (ur G) (ur ur) (ur P)]
Game 3 W50-42 11k 10a 8d [(ur P) (ur P) (ur P) (ur P)]
Game 4 W50-32 9k 3a 7d [(ur D) (ur P) (ur P) (ur G)]
Game 5 W50-49 13k 3a 11d [(P P) (ur P) (P P) (ur P)]
Game 6 L31-50 7k 2a 12d [(S O) (ur D) (D O) (ur ur)]
Game 7 L28-50 8k 4a 10d [(P O) (ur D) (P P) (P P)]
Game 8 L29-50 9k 4a 12d [(ur P) (ur P) (ur P) (ur P)]
Game 9 W50-40 13k 7a 14d [(P P) (P P) (ur D) (ur P)]
Game 10 W32-2 7k 4a 0d [(P P) (ur P) (ur P) (G G)]
key: ur = unranked B = Bronze S = Silver
G = Gold P = Platinum D = Diamond
O = Onyx C = Champion
Let's break this data up even further. Here's 3 tables of how your record against higher ranked, lower ranked, and equally ranked opponents is based on your at the time ranking, your current ranking, your opponents' at the time rankings, and your opponents' current rankings.
Code:
NOTE: Records will sum up to 40(10 matches against 4 players)
Higher
Opponents > ATT Curr
You v
At the time 6-5 27-11
Current 0-1 2-5
Lower
Opponents > ATT Curr
You v
ATT 0-0 0-0
Current 23-8 7-1
Equal
Opponents > ATT Curr
You v
ATT 22-7 1-1
Current 5-3 19-6
What these say is that during your placements, you went 6-5 against opponents that were higher levels than "Unranked". There aren't any opponents lower than unranked. You went 22-7 against opponents who were also unranked. This means while the system was placing you, there was essentially 72.5% uncertainty on where to place you. If we take the bottom right portion of each section, you were 2-5 against opponents higher than your current ranking. 7-1 against players lower than Platinum. And the important one is 19-6 against those that are the same rank as you.
The system is basically saying you are better than the other people that it initially ranked with you. Therefore, we need to match you against opponents that will determine if you truly are better. The only way the system can do that is if you play against those that are at higher levels than you.
Yes, the system still needs some tweaks. I got placed into Champions for Rumble Rockets, and that was only because I got placed so early on. It has some issues, but your rank is not one of the issues.