Even if the punches were as slow as the guy in the link below you're going to have a hard time getting in unless you train for this.
http://www.rmax.tv/images/fisticuffs.wmv
You have to remember, if you do not train to react to certain things like take downs, punches, and kicks, and the guy trains to do those things. You're chances have just diminished. Lets just thank everyone around for being too lazy to train in doing those things.