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Weird Rating Deviation for player. Is this a bug or just a quirk of RD?

I just finished a game with a user named marsam (http://en.lichess.org/@/marsam/). He seems to gain or lose a lot of points with each win or loss. Of course, that all sounds perfectly normal for Glicko2 when a player has a high RD because they've played very few games (or not played for a while), but I glanced through his blitz game history and he's played thousands of games and over a hundred in the last week alone. Even after all of these games he's still gaining or losing a large number points with each one; way more than I'd expect for someone who should have a low RD by now. I recorded the points he gained or lost in each of his last 100 rated blitz games, all against regular looking opponents near enough to his rating, starting from last Tuesday (less than a week ago!) to show you what I mean.

[Last week -> 42, -43, -36, -34, 58, 51, 31, 22, 21, 19, -70, -61, -53, -44, 41, 35, -29, 34, -40, 42, 36, -15 (Draw), 27, -57, 31, 28, -37, 48, 41, -39, 45, 38, -45, -39, -33, -30, 38, 32, 43, -48, -42, 38, -50, 34, 30, 27, -30, -25, -34, 52, 29, 25, -58, -52, -43, -38, -30, -27, -24, -40, 34, -40, 47, 41, 34, -9 (Draw), 31, 27, 24, 22, 19, 18, 17, 15, -77, -49, -42, -28, 48, 41, 34, -51, -44, 63, 32, 28, 24, -31, 55, 24, -60, -24, -24, 37, -49, 39, -41, 27, -53, -26 -> Today]

It only seems to affect his blitz games, and not bullet. I'm very sorry to bother you if I'm missing some quirk about Glicko2 Rating Deviation that might cause this, but I've never seen anything like it and thought there was a good chance it is some kind of bug. If so, this poor guys blitz rating is just bouncing around like crazy, and it might be affecting some other users as well.
Worth noting that all of his games are against players +/- 100 points of him, but only where he is at the time. And with these crazy swings, he goes from 1600 - 1800 in a matter of hours, and back again. Could be a quirk of it giving you a slightly higher RD after your rating bumps, which has sort of "resonated" after a bunch of ups and downs making it hard for him to settle into a score range?

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