What changed around 92/93? Coe and Ferigno both did the Masters at this time and both were bigger and leaner than ever. That's the same year Dorian made the leap from good to other worldly.
I mean Boyer competed in dozens of shows from the late 60's to the 80's.... then comes back at 45 bigger and more ripped than ever? Louie too? Louie was insanely huge at that time. What changed. Everyone was saying it was HGH but that's still not clear what effect gh has on muscle size other than the increased hunger/appetite and calorie surplus.
It was the GH 100%. In a high dose it can have dramatic visual effects on some, whatever the exact mechanisms. Remember, Lou also had carpal tunnel surgery at the time and I don't think it was a coincidence. Benfatto also did a similar transformation.