Fact is, when you push "things" as far as these guys do, you have to expect to pay the price, somewhere down the line. Dorian did all he thought he needed to to become the world's best, and now Mother Nature is collecting payment.
Most every contemporary (say, the last 20 years) high-level bodybuilder eventually suffers Disappearing Triceps Syndrome (I came up with that a few years ago), and when you couple this with Yates' injuries, etc., it's obvious why his upper arms are so trashed.
The man is a legend and a nice dude. I sat with him a few years ago for lunch in Toronto and, yeah, he's, overall, still a large man, but his upper arms are withered and destroyed. But at this point, what does he have to prove? He did what was necessary and reaped the rewards. Now his bodybuilding glory days are long over and he's very fortunate to have the health that he does, as has been said.