It just goes to show you, that even these "elite pros" are still human.
We can only guess at their REAL diet/training/supplement/drug regimens, but when they take time off... many of them lose size and strength very rapidly.
Big Ramy took 2 months off from his protocols, and lost 30-40lbs: Going from 335+lbs to 306lbs.
I think it's just basic physiology.... if you take away all the anabolic drugs, the extreme amounts of food, and heavy-duty training regimens, the body has no reason to remain "huge".
For what it's worth, I used to observe the same phenomenon happen to Ronnie Coleman (when I used to train at Metroflex). This may not be well publicized, but it was true.
Each year after the Olympia, Ronnie would take a long break, and come back to the gym in January. When he returned in early January, it appeared that he was easily weighing 30+ lbs less than he was at the Olympia.
He looked much smaller, softer, flatter... like a different man really. However, within a few months of his "regimen", he was back to being a monster in Febuary or March.
I shit you not: I happened to be there on his first day back from one of his lay-offs one year, and he doing a chest workout in the afternoon in January. He asked me to "spot him" because was struggling with 120lb DBs on his chest workout. He was obviously able to press them, but he was struggling with about 8-10 reps. (Within 6 weeks, he was back to reppin' the 200s.... while most of us looked the same.)