Is MMR really a reliable measure of skill? Games feel random lately

Let me give you some Context.

I have two accounts that I play ranked with. No, the point was not just for the sake of smurfing. I started practing new heroes on the alternate account. My main is sitting at Divine 2 to this day, 4930 mmr. I mostly play offlane there. After a couple of months I managed to put my second account on Divine 2 too, playing pos4 and pos5. I was kinda stuck at that rank for like two months, around 50% winrate, I felt like I belong there. It felt like the mmr system was actually accurate for some time.

Weird thing started like 2 weeks ago. I went into an unbeliavable lose streak for no apparent reason. Like I dont think I'm playing any different/worse than I was. First I lost 15 out of 16 games. I thought it was an unlucky streak and things would turn around. I had losing streaks in the past and always bounced back so I was not really too much tilted , just a bit, you know. But after that I am still losing way more games than winning. Like I lose 6 , win 2 maybe. I dropped from 4930 to 4200 mmr in one of my accounts in the spam of 2 weeks and I'm still losing. At this pace I'll hit below 4k in a couple of days.

I dont think it was because of the new patch to be honest. Cause after patch was introduced I was still keeping a 50% winrate at div 2 for a couple weeks. the loss streak came from nowhere. I would say that 80% of my games feel like complete random fiestas. Nothing really makes sense. People afk in the first minutes showing they are not really putting effort, or they pick the most absurd stuff you could imagine for their roles , people gigafeeding in the first 15 minutes and ragebuying back. Ppl breaking items. Team Flaming each other nonstop and giving up easily. You may think, well, enemy team is probably having trouble too. Not really, at least nowhere near as often as mine. I checked a lot of my replays and to be fair the vast majority of these games felt unfair. Like my team was sabotaged from beggining. I felt like I did well in most of these matches. Like I either won or draw 90% of my lanes. I was playing support and seems like it doesnt matter how hard my lane is won. the second i turn back back to do something important, the core will immediatly die and throw away the lead I fought so hard to build and from there its downhill.

So now I'm in this weird spot where I have One account div2 and the other ancient 3 ( almost ancient 2). Which puts thoughts into my mind. Is match making in dota really a consistent measure of skill? I'm not feeling like it is. Because my winrate in the past couple weeks is abysmal, like if I were a 2k player playing in ancient/divine, There's no way I woke up one day and forgot how to play dota. Any thoughts?