frustration again
I think you take your higher rating for granted. You should focus and learn on making good moves by analysis or tutorial. I am sure you made lots of mistakes when beating 1900s and you got lucky to got rewarded. And you are making same crappy mistake now against 1650s but now you are not getting lucky and so your rating is dropping. I think you are the same player when you are at 1900s and 1700s. But in reality there is skill gap of 200 rating point which you don't. So you are now at 1650s. First making good moves, then result and after that comes the ratings