Weight is not the only thing that constitutes a show quality bird.
There is a "flow" to a white Rock. Your bird does not exhibit it. His tail angle is too high, his head is too narrow, the wing feathers are not tucked in and held close to the body as in a good bird.
There is nothing wrong with having a pet quality bird. They will make good yard ornaments as well as keep you in good supply of eggs (well, obviously not him seeing as how he is a rooster) and can make very good pets. He may do well in a local show, but if he is competing against birds bred towards the standard, he will not place well.
You are entitled to your own opinion, I am simply stating what is preferred in the standard of perfection and what the judge will desire in a bird if he is judging towards the standard.
Here are some of the issues I see with your bird:
Standard calls for: Back: Rather long, broad its entire length, flat at shoulders, nearly horizontal from neck to saddle, then showing a slight concave sweep to tail.
What I see in your bird: Back: The back looks short, and slopes downward. It could be the angle of the photo. There is no sweep to the tail. The back and the tail just sort of "push" together making the odd angle.
Standard Tail: Medium length, moderately spread carried at an angle of thirty degrees above horizontal.
What I see: Length is ok, the tail is tightly put together and the angle is greater than thirty degrees.
Wings: Medium size, well folded, lower edge of folded wing nearly horizontal. Fronts, well covered by breast feathers and points well covered by saddle feathers. Primaries and Secondaries--board and overlapping in natural order when wing is folded.
What I see: The wings are not folded, the lower and edge points towards the ground. The fronts of the wings are not well covered and the points are not covered by the saddle feathers.
These are just some of the things I am seeing upon immediate inspection. I am not saying that you should not keep him for enjoyment, only that he is not a bird bred towards the Standard for the breed.