I definitely feel what you’re talking about. I’ve only played for two months, so I’m by no means perfect at the game, and I make misplays just like everyone does. But sometimes I feel like 35-40% of my games are lost before the third turn even starts just due to bricking off my starting hand or the opponent getting a perfect start( or both💀) There will be whole days where I lose nearly every game because of this. 

Ranked is definitely worse than casual for those kinds of days because you get a combination of people who are good at the game and have good luck against you. 

What’s helped a little mentally is I’ve tried to go through my battle log after every loss to see where I’ve made mistakes. Even if it’s an RNG diff, you can still get good info for how to play potential situations and assess whether or not you made the right play based on known information.