He once said that he puts on muscle in camp and looses some of it when he doesnt have a fight scheduled.
It's not to say by taking up a training regimen the average person can't see results. They will as long as they train properly, which you pointed out. That is not the issue- the issue is developing a physique similar to Wlad's you have to resort to steroids. Now I doubt a video of someone injecting Wlad in the ass is ever going to come out so of course there will probably never be "concrete proof" he is in a fact a steroid user, but you just have to be suspicious of any of these monsters with huge muscles and very low body fat.