In the first side by side set you can see the difference everywhere which I know is one of your points: an advance bber can get bigger all over but can't change natural proportions. One would have to have a very discerning eye, or "wishful" eye to determine if his back improved proportionately more than the others.
In the next set where he is closer in bodyweight, which was pretty consistent throughout his career (except in 2009) you can see in the second pic that he has more fullness in his traps all the way down to the middle back and his lats are wider. They jut out more at it's widest or peaked position as it were. That is one thing I thought was most noticeable later in his career. The way his lats flared out more when doing a front double bi, which, ironically, can't see to find.
Thanks for the pics. You could be right about the traps or the flare on the lats but for me it's very hard to draw those conclusions just based on this. And the reason is that the pics are not taken at exactly the same angle in the second set. He is crunching his back more in the first pic there also.
The first set is so similar that it could have been taken on the same day as far as I'm concerned, are you sure it's not?

It could be predjudge vs. night show where he combed up his hair

Fans often see major differences between predjudging and night show too, and even there I think the differences might be mostly imaginary as you can't compare side by side but go by memory. Hell, some feel the physiques change drastically within 10 minutes during the rounds.

Anyhow, Dillet's back was so comparatively small that he could have added an inch of lat mass and it still would have been undersized.
Someone in this thread said Lee P said Dillet shot a lot of shit at random. Where did he say this? I remember an early interview where Lee swore Dillet used very little gear and the two of them would skip shots for days - and Lee knew this because they were roommates. I read some claim that Dillet only used Anadrol off season, nothing else. Whatever the truth, Dillet had alien genetics for most bodyparts.
*edit: noticed the worm already said the same things above*