Interesting conversation. But, a number of things on here worry me.
1. First Pfaff is not a dirty coach. Athletes do things all the time against the wishes of their coach. Marion Jones is a great example of this as she jumped between a number of different coaches along with jumping between a number of different lovers. She is not to be trusted and shouldn't be held as the standard against to a great coach like Pfaff.
2. Usain can be clean. Just because he improved and is faster then any clean or dirty again means nothing. We are quick to point to dope. Considering his early talent, with terrible work ethic, suspect coaching, bad start, and scoliosis. That is a huge amount of things that were changed or treated to help him become the runner he is today.
3. I think steroids have less of an effect if you are doing everything right. Sadly a lot of this new crop of athletes are coache by thugs who hav no clue how to coach. Instead these thugs are just trying to make a name for themselves at all costs. A lot of of ego is involved in world class sprinting. Now these former diva athletes have the name Id and have become diva coaches. These are the people who are most killing our sport.
4. People improve a .2 in the hundred is not impossible. Even from 10.0 to 9.8 or faster. You act as if coaching, periodization and training doesn't have an effect. Athletes improve all the time. Think about just improved reaction time and new drive phase can do that. What about dropping five unnecessary pounds? All the British sprinters could be lighter (except for Gemili and Dasole) and would ran faster.
5. Just because someone runs great one year a slow the next means nothing. Speaking from experience I have a lot of athletes assassinate their fitness all the time. This can happen in few short months and takes much longer to get back in shape.
6. Just because you were elite doesn't mean you can make bold, unsubstantiated statements, without considering many of the above mentioned items above in this post.