In my opinion, the nose bridge says it all.
You can see in the before picture that he had a very slight bump at his nose bridge, i.e. the bony part of his nose.
His face would be much more harmonious if his maxilla were advanced to the point that the lower part of his nose (the non-bony part) went forward just enough to create a straight nose profile—in other words, just enough to bring it into line with the upper, bony half of the nose and eliminate the slight bump at the bridge.
Instead, they advanced it to the point where the lower part of his nose went so far forward with respect to the upper part, that his nasal profile now looks scooped out.
I’m not an expert, but this is just an observation I’ve made that seems to have stood up with time after looking at many jaw surgery results. This appears to be related to ‘anatomical correctness’. Anatomically correct looks right. Anatomically incorrect looks ‘off.’
Perhaps someone with more knowledge could comment on the validity of this theory?