A57 Images Are Soft!

I have this issue too. Most often indoors. a57 with Sony SSM16-50/2.8. I bump up to ISO800 indoors, photographing my nephew. I can tell the difference between blur from him moving. It just seems like sometime the lens doesn't focus on anything and I get soft images. This one below as an example. Even stopped down to f5.6 it still doesn't appear that anything in the picture is in sharp focus.

ISO-800 f5.6 1/50th. SS on, aperture priority mode. Due to the subject I also have continuous shooting turned on as well as autofocus set to continuous. It is supposed to continue autofocusing inbetween continuous shooting right? Even when I do a burst which is most of the time, all the images in the sequence will have the same unfocused quality.