Looks like they are out of focus, are you using manual focus or letting the camera do the work, I find manual is the way to go with stuff like this, you will get lots of rubbish ones before you get a good one, as bats are really quick! But because of that your camera will have a hard time trying to keep up and focus.
What sort of shutter speeds are you getting as well, as thats going to be key, your using Aperture priority at the moment, I would have a go with full manual or at least shutter priority.
Also if you can get away with closing the aperture a bit might give you more focal range, but shutter speed will suffer because of that.
Alternatively get yourself up on the roof to get a bit closer and put the flash on