I'd say it's a combination of Bad Genetics & him not knowing how to
train / use the best exercise to make the most of his awful Genetics
25+ yrs of Steroids/ GH / & other to achieve that awful body !!
Lack of knowledge / won't take advice
Lazy - wont train hard
Won't eat correctly
Bad Genetic response to the light training he does
& Bad Genetics response to his PED use.
I think a lot of this stuff is genenetic in terms of muscle shape, insertions etc.
I've done all the stuff - rows for days, slow controlled, squeeze in the middle, pull ups, deadlifts, big weight, light weight, hitting failure etc.....I don't have any pop back there.
It just is what it is sometimes.