A critical part of coaching and a clean athlete's preparation is to design a system in which the athlete is at a maximum at race time. I do believe that training gives large positive benefits--but at least in the world of sprinting, those benefits are only manifested in small windows of time.
What do I mean? I mean that a highly-trained clean athlete can go 10-flat when they peak, when they are feeling just great, when everything is going just right. Their maximum. On the other hand, a doped athlete can deliver the same type of performance--their maximum--consistently, and multiple times, over large stretches in time and space.
I personally have felt natural highs, during which I measured my performance later in life, just out of curiosity. At one point my PB for the year was 11.7 in the 100m. When I was timed during a workout in which I happened to be feeling great, I went 10.9, and it was a solid 10.9, let's say 11.1 with reaction time. A huge difference.
Could I deliver it when needed? Of course not, track was not my focus in life, and I had no set program and no coach. A good coach and program could have gotten it out of me at race time. From my experience, had I been using, I could have delivered that max performance any time of day, any day of the week, anywhere. That is a HUGE (but not the only) advantage of doping, at least in the sprint world.
So while Renato you may be a great coach in the sense that you can get your athletes to deliver their maximum performance exactly when it counts, other coaches may not be so great--and in that case (at least in the sprint world), doping can make a huge difference. Even if they don't improve absolute maximum performance ability, they do combat the effects of a weak program and weak coaching, and enable the maximum performance to be produced when it counts.
I would like to hear your thoughts on this in the world of distance running.