For one, we should remember that when these pics are taken, they are taken in near perfect lighting and the bodybuilders are pumped to shit.
...and don't underestimate the impact that living in an environment like this can have, where everything is perfectly tailored towards the bodybuilding lifestyle.
Increlex may or may not be available there, but in my mind it is irrelevant, as IGF-1 is not hard to produce and doesn't cause massive physique transformations like some people think. It can help, but it certainly isn't as powerful as steroids in this regard.
Remember, just because someone is a pro bodybuilder it does not mean they are perfectly applying themselves in every area of their program. In fact, most pros are NOT...so when they go over there and virtually everything is set-up for success (including everyone else doing the same thing), it is not surprising to see some of these guys making progress.
Also, think about how many pros have gone over there and haven't made much, if any progress? Dennis Wolf (who is a very dedicated bodybuilder) went over there and made no meaningful progress. He is just one of many. It is usually only the guys who are far from their genetic limit--the guys who are not nearly as dedicated to their craft (Like Curry)--who make great progress. Any top bodybuilder I've seen go over there who has already dedicated himself to this sport 100% doesn't make stellar progress. All the guys who have are those who are still coming up or who never fully applied themselves. If some drug concoction was responsible for these changes, then EVERYONE would be making these same changes...but they're not. For the most part, it's only the guys who fit into that one group.