Yeah, I noticed this for the last week to week and a half or so. I mentioned in my arena thread that my last deck seemed to have extremely strange ratings gains/losses. My deck lasted way longer than it should have, because it was not losing much rating on a loss. Looking at that screenshot, 162 for 1st and 83 for second is... extremely low. The deck I have up now is 9-9 in plat (normally impossible), has rating -273 (I think normally you're out of top 500 by -200 roughly) and it's still at rank 329. Every once in awhile this sort of thing seems to happen; perhaps some hacker is doing something to make plat really easy to farm, like setting opponent's hp to 1 every game and then running a bot to farm.