A55 and Micro focusing Soft Picture example provided

Just wondering if micro focusing is firmware for a camera or is it a built in feature in a camera? I find myself trying to use manual focus more and more. Some of my shots look soft on the LCD and now that I am home they look better than thought.

When I look at the pictures in the field I find them to look soft but when viewing them on my PC screen they look better. Why is that? I use the zoom button to help decide if the sharpness is good. Is that not a good indicator? Here is an example of a picture I zoomed on in the field and it looked soft.