You don't need a particularly good handle of lighting to understand that the vast difference of those photos versus most of the bad lit stages.
Those photos have shadows, ie, the lighting is directional enough to throw some depth into the pictures.
Badly lit comps have more universal lighting that disallows shadowing, which washes the bodybuilders out and hides their actual size.
That's why when you were looking at the kamali kitchen classic or dennis james precontest photos, you were always blown away by the fact they "fade" when going to stage. Well, no, it's just that every one of the pros up there look amazing in more regular light. As soon as you shine all that olympia light on, you get this situation where they say "what happened to Levrone?". Nothing happened. He didn't fuck something up, he wasn't much bigger at the press conference - the lighting was different. The lighting at the press conference gave depth.