Don't think he was on "gear". Might have used a ton of prohormones, the legal ones and hey might have helped him, who knows. But I think it has all with the diet, training and so on to do. If the guy never trained in his hole life and suddenly started to workout with a nice program and high carb/protein diet I think those gains would be possible. If you don't do anything else than just train, eat, eat, eat, eat, rest and rest some more then you will grow like crazy, no need for gear for a newbie in the gym.