Are some people just bad at Dota?

I have been playing this game on and off since I was a teenager ten years ago. I took a couple years off before dota 2 came out. I came back and started playing a bunch and started to feel like I was getting pretty good but then slowly started to feel like I was getting worse and worse. I calibrated at 3.6k and slowly sunk down to 3k. Is it just that I am bad and won't get better?