As I see it, roleplaying and combat are entirely different ball games.
In combat, the players are on equal footing with the DM. The DM's monsters and NPCs must roll their dice to make any engagement with the PCs.
Outside of combat, the DM is God. The DM no longer needs to roll her dice to affect ANYTHING relating to the players. Storms may blast down doors, dung beetles may fall from the sky, and NPCs may score multiple critical hits without the DM touching her dice.
However, your players must trust that what you do outside of combat is fun, exciting, and even in misfortune shall grant them a piece of the spotlight. If a commoner has knocked them out with one punch, then make it entertaining. The player neglected to notice that the tavern floor was wet with ale and slipped in the exact instance that the commoner threw his punch. The commoner broke his hand on the player's jaw but it gained him some respect in the tavern. The next day, the commoner comes to the player, his henpecking wife dragging him by the ear, and apologizes in front of the WHOLE tavern for causing a fight. Alternatively, if a tough-as-nails SOB knocks one of the players out with one punch, play this guy out like he chews razor blades and treats his wounds with sawdust. Make it seem like the characters were lucky they pissed him off on a good day. You know any Chuck Norris jokes? The tavern folk talk about this guy like that.