How do you go on a 20 something loss streak if you are roughly appropriately ranked?! If u have a 50% chance of winning against an on-level opponent you have a 0.5^20=0.000000095 chance of losing 20 times in a row, except that as you lose your games your opponent will on average get worse so you should now have a more than 50% chance of winning and so that probability is even lower...
I would have accepted the argument you got unlucky a lot and got overmatched opponents queueing at bad times but then you wouldn't have lost much elo and hence many ranks for losing to the much better players so wouldn't have plummeted to 2000 which is in the bottom half of the ladder. And the fact you levelled out back to only 1500 suggests either there was something dodgy about your rank 400 or you got substantially worse (?).
I've never lost more than 5 games in a row in 1v1! And over my time playing many RTSs I've almost never gone on loss streaks on more than 4-5 games in a row.
The problem is that when you launch into a game of 1v1 of coh2, even if your elo rank is equivalent to your opponent's, you won't have a fifty percent chance to win.
As ranks fluctuate, different units come into play, different strategies, commanders, etc.
The last game I lost was when I was above rank 2,000. It was on semoskiy winter against soviet industry tactics.
Now, at that stage in the meta (about a year ago, I believe) soviet industry was almost never seen in 1v1. Or, at least, I had not encountered it in quite a while. I was on the back foot, wasn't as good as I was now. Using Gren/fausts and PaK40s to counter multiple T70s is hard. Then came the T34s and it was just unstoppable.
I've come quite a ways since then; watching ESL has helped, I think, but it was definitely a frustrating match. So much so that I remember it vividly. My opponent's infantry micro was terrible but I was so scarred into thinking that ostheer can't be aggressive and that I must maintain my little bubble of defense on semoskiy.
Anyway, you can't assume that there's a 50% chance of winning among equal players. Shit happens that you don't expect/prepare for, RNG can be unmerciful, or you can be tired af but still playing coh2 because you've got nothing better to do with your life.