I'll start. (Yes I know this guy looks like a metrosexual cum guzzling fruitcake, but i'm just using this pic to prove a point) This is the kind of physique you can expect naturally.
Any more mass and you'll get soft and bloofy.
As a natural this is the kind of mass you can shoot for while still being cut.

If that guy went to the gym instead of focusing almost soley on diet for leaness he could be a lot bigger as a natural.
I'd bet all he does is cardio, like cycling or jogging and maybe 'core' exercises on the swiss ball and a few light weights to 'tone'.
His arms are very skinny, any natural who lifts weights for at least a year could have bigger arms.
Not saying it's a bad physique, he looks fit and in shape, but doesn't look like he lifts weights though.