He didn't deck her. Look closely. He gave her a leg sweep. The fist never hit her, it made her scared and he came in with the leg sweep, and she fell like a bag of potatoes. lol
Also, getting beer in your face is a lot more horrible than you thing. That shit burns in your eye, and it gets sticky right away and almost impossible to rid of the smell. How do I know? Someone threw a beer, the guy dodged it, I turned my head and got it lol. It was at a concert, I didn't care cause I'm pretty much already wasted... but I regretted it later when I got home.