Damage/Crit reduction testing

Lets say if Girgashiy really have high defense, we would be dealing him 1s no? I used bare-handed and hit him with it, I deal more than 1 damage, so that was not "defense" stat. Take Ghast (All types) for example, he has very high defense, 5-20% damage reduction [Different for each type] (Protection Value of 3-27), you hit him, almost near 1s or low damage right? but when you critical on him, you deal really high damage, much more than hitting him without critical. I slightly remember, as due to SAO Peaca Zone 4/5. my gun damaged Red/Blue Ghast by 1s without critical and with critical, it deals over 1,500. Then again other than Ghast, there aren't any other monsters/boss that have very high defense to begin with.