new puzzle scoring system

I have looked at other profiles and found people whose scores have not changed at all, others who have lost between 300 and 500 points, and others whose scores have dropped between 800 and 1200 points. None were reset to 400 (I haven't seen a profile like mine!) and certainly none did ridiculous puzzles with a rating below 1000-1700 in the days leading up to 9 October or afterwards. I, on the other hand, have been unfairly robbed of almost 31,000 points, and even though I have the settings on extra hard, all the puzzles are mate in 1 and do not exceed a rating of 700 or so. 

I have looked at other profiles and found people whose scores have not changed at all, others who have lost between 300 and 500 points, and others whose scores have dropped between 800 and 1200 points. None were reset to 400 (I haven't seen a profile like mine!) and certainly none did ridiculous puzzles with a rating below 1000-1700 in the days leading up to 9 October or afterwards. I, on the other hand, have been unfairly robbed of almost 31,000 points, and even though I have the settings on extra hard, all the puzzles are mate in 1 and do not exceed a rating of 700 or so. 

There was something really strange with your puzzles even before the change. You had a rating around 3500, yet the system kept giving you puzzles rated only about 400. As far as I understand, the puzzle difficulty should also increase as your rating increases. Hardly your fault though. So you were solving easy puzzles the whole time, and because of the old +5 minimum gain rule, every correct answer still gave points. That’s how the rating just kept inflating.

After the rerun with the new (more ELO like) formula, those artificial +5s disappeared. In Elo terms, if someone solves 400-rated puzzles with an 85% success rate (as you had), their real equilibrium rating (unless I ran the numbers wrong) would be around 700. Your new rating of 638 is actually quite close to that figure. and the difference can easily be explained by lets say that the average strength of the puzzles was bit lower than 400. So the logic seems right.

The strange thing to me is why you were given only easy puzzles making it essentially impossible for you to increase your rating. The system did not serve you well here and I can see why it would seem unfair.

If someone was getting 400 then their rating history had been reset. If they were also on Standard difficulty, they would get low rated puzzles for a while, until the rating increased sufficiently.

My rating history does not look like it had been reset, yet I was getting not easy but trivial puzzles and even after choosing Extra Hard difficulty, the puzzles were so easy that I had a success streak of 140 puzzles until they became sufficiently difficult.

And @Honor_Leslie has a maximum rating of 3558 according to the new rating system, but on September 29 apparently crashed to 400, also without this being visible in the history graph.