How do people do SO much damage?

I just got the game after seeing it on the interwebs and it looks so fun but I always get outdamaged every match. Usually it’s someone flailing their arms and getting a lot of red hits and I get knocked out. I use head movement and angles like I do in person but I just lost to a guy swinging his arms at my body and then head nonstop half of the stuff missed but the amount of damage he does changes so much of the game cuz I lose the decision. It gets ridiculous to the point where I did 800 damage and they do 1200+ I don’t get how they do it :(