Totally disagree here, it was 100% genetics, he didn't train his back any less intense then he trained his front, yet his front looked amazing. His back was genetically flawed, it lacked a lot of lines and the few lines he did have were very shallow, his back lacked separation and the size of certain back muscles where lagging in response to his genetic limitation, all his problems from his back where due to genetic limitations, nothing to do with training
I always thought he lacked detail...but, I think if what you said was true, then Nasser genetically blessed with a shifty back. Nope---it was the big man's curse---only big from the front.
If you ever seen some of Dillet's back training vids---which I've only seen him do lat pull downs, he would just go thru the motions.
He never took time to pose, flex...and even his posing he just "hit shots". When he trained his front, he was a pumper...you can get away with that with arms, chest...but with back you can't slack.
It's easy to develop your front, you know that yourself as a competitor. The big dudes only focused on the show pieces. And like I said, he was wider in his arms outstretched pose than when he did a lat spread. That shows something right there, possibly a lack of practice and mind muscle connection.