
man.
Theres a few problems with your problem..
With the first pic, it is soft and out of focus. (probably due to your lens 75-300). With lenses like that, it's softer especially at 300mm. Also your shutter speed of 1/500 is too slow for your focal length. With the 1/focal length in mind. Your shutter speed should be 1/500... OH SHIT /facepalm
Anyway i'll continue explaining, with your focal length of 300mm x your 1.6x crop factor = min shutter of 1/480 so 1/500 is right. How are you holding your camera? The way you hold it also makes a huge difference.
Also check out this guide here on composition. Centering an object is
rarely ever good.
http://www.digital-photography-school.com/digital-photography-composition-tips