What’s happening with the skill distribution?

Not entirely sure what the skill assessment algorithm is looking at exactly, but...

If you've always been on the left side of the spectrum and are now ending up right side a lot then one of two things is possible. Either the game thinks you're getting better (look carefully at your avg. damage, especially in relation to your avg. match length), or the game is doing what it always does with solo queue players, which is to say, assembling a squad of randoms out of very mis-matched players. If you're getting a run of games where you are the "weak link" and your squadmates appear to be able to hold their own, then scenario two is what you're experiencing. Or possibly a combination of both.

Good test to try: Do one match "no fill" and the distribution curve you see will show you exactly what mmr the game has currently assigned you. That's the red line on the graph. Without squadmates that data point IS your skill level. If it's higher up the range than you think it should be then you have some work ahead of you to actively push it back down. To do that, essentially stop trying so hard. The less hard you work for your inevitable bad result then the quicker your mmr will come down. But it still won't be fast. If, on the other hand, your mmr is left-ish, more or less where you thought it would be, then you're just on at low population times and the server is scrounging the left side in order to fill right side lobbies. In which case the ONLY thing you have to do is quit and re-queue until you start getting the curve you feel is appropriate. The one thing you DON'T have to do is just accept the match quality the game decides to give you. At least not in pubs.

Best of luck.