The main reason walker et al suck so much is that the current way of doing things is skewed from the start. None of these guys spent a decade building made the hard way, by training with heavy free weights, even heath built a foundation first, machines came later. Now these guys blow up with synthol insulin and GH and when it's time to diet they can't stay in a deficit because the temporary fake size they have vanishes leading to DNP abuse to lean out. As the DNP is cooking them their coaches are injecting SEO everywhere in an attempt to stay "full' because only in the off season do they look competitive size wise so what they are attempting is basically impossible. What we see on stage time and time again are failures due to laziness and incompetence. Samson for example turned pro just a few years after he started training. I remember seeing him winning amateur shows and being shocked how obvious it was that he was abusing synthol. Theres no other way to make gains that fast. Most all of these guys are using it everywhere look at andrew jacked FFS. 
So you take a body and fill all the major muscle groups with oil and when they lose fat there's still synthol everywhere leaking from injection sites for years. It wouldn't surprise me if synthol is interfering with fat loss but even if it doesn't it surely causes massive systemic inflammation. If anyone has seen these guys blood work I bet you'll find sky high crp and il6 levels. 
But anyway, bottom line is these guys are weak and can't do any better because no one is really leading the way. Haney Yates etc were excellent role models and took the sport in the right direction. Bodybuilding has lost its way.