Question about jaw implants looking bulky rather than aesthetic?

Jaw angle implants seem to be a bit hit and miss; sometimes they look great, other times they just make the face look bulkier and puffier. Why is this? Is it down to masseter muscle insertion points like in the image I’ve linked? And if so, do custom implants that vertically lengthen as well as slightly widen help prevent this puffy issue from occurring? In the less than ideal results I’ve seen, faces are wider, yet, but not necessarily better. Many thanks!