Most guys can't afford big lenses, so they are stuck with cheap zoom lenses. Zoom lenses are typically not as sharp as a fixed focal length lenses. Also, zoom lenses usually have a sharp and less-than-sharp zones. Usually the worst sharpness zone for a zoom lies at full extension. And in surfing, you almost always need as much zoom as you can get.
So we have three factors here contributing to bad quality shot.
Cheap glass
Zoom lens
Zoom lens fully extended
Add to this, the shot you're seeing above is likely a crop, to make the surfer look bigger in the image. If they cropped the shot, then enlarged the remaining portion, this also brings down the quality. In this case, a higher mp camera can offer more pixels to work with, although higher mp doesn't mean better shot.
Also, the lighting is horrible in that shot. No sun means no shadows which means no depth.
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