What exactly did he do wrong?
I suppose that lichess changed puzzle rating calculation. Gliko is equavalent Elo if games (puzzles) occur often (RD is stable). Now when I lost and difference between my and puzzle rating is 300 my rating decreases by 29 (must be ~ -25 if RD = 30). When I win I get right addition to rating ~5. So at present rating calcultion is not consistent.
A couple of points here:
1. My proposed ratings patch was rejected for performance concerns but might be (hopefully will be) replaced by a performant patch.
2. Under Glicko-2, puzzles being frequent doesn't guarantee a stable RD, in the same way that a 2500 playing against 800s all day isn't guaranteed a low RD. Granted, given the way Lichess selects puzzles by default -- for people not typing puzzle IDs into the URL -- probably helps stabilize player RDs and puzzle RDs.
Once I thought
@ToadofSky was wrong but he was merely mistaken
