Ilemy actually makes some good points here.
In summer 2007 Bolt went 10.03 (+0.7) in his first real 100m.
In early May 2008, he went 9.76 (+1.8), then in late May went 9.72 (+1.7) for the WR. In mid-August he went 9.69 (0.0) while goofing and negative-leaning, with an untied shoe, which in reality was around a 9.55-quality sprint.
So he went from 10.07 in 2007, to 9.84 and 9.80 in early 2008, to 9.55 in late summer 2008 (adjusted times).
I think the 10.07 in 2007 should be discounted from the trajectory, because what it amounts to is a "try-it-and-see-what-happens" kind of race. Believe me, the start, drive phase, and speed envelope of the 100m are not like they are in the 200m, and Bolt's 10.07 should not be taken as any sort of approximation of his trained 100m potential at that time.
So, we are left with a guy who realized in 2007 that he could be fast, and in a little under a year runs 9.84/9.80 adjusted. The actual improvement during that time was therefore around .25 seconds, which is easily accounted-for by a year's worth of 100m training, and which would not necessarily, by itself, be good evidence of juicing.
The problem is the lowering to 9.55 a mere 2.5 months later, which represents another .27 improvement, which makes an over half second improvement (.52) in basically one year's time.
To be fair, Bolt had good fitness entering 2007 and 2008, from his 200m training--really, all that he lacked were the finer points of the 100m.
Yes, it is possible for an exceptional athlete to master the finer points of the 100m in a single year. The only question remains, how much improvement is reasonable to rationally expect, given his starting point?
Again, he was well-trained when he ran that 10.07, in terms of sprinting fitness if not in pure 100m technique. Can a year's worth of technique training result in a .52 improvement? Maybe. Can a year's worth of technique training combined with a year's worth of natural development at a critical time result in a .52 improvement? Absolutely. Did it? In my opinion, no.
It strains credibility. He wasn't just improving, he was improving to a point beyond anybody's conception. No matter what BJ says, even he couldn't have gone 9.55 adjusted. There IS a chance that Bolt is the historical anomaly of all-time, but it is intrinsically exceedingly unlikely.
Then there is the matter of injury. Bolt had been injured in the past, but all of a sudden he is doing block starts and driving, and he emerges uninjured in 2008? Rationally, that is not likely, especially considering that it was his first year of dedicated 100m training.
Then there is the fact that the 9.55 was done after rounds, meaning that it might have been 9.50 fresh (coach has been quoted as having said 9.52 was possible). That would have pushed the improvement from .52 to .57, further into the absurd territory.
Why is .52 absurd? I personally can't think of any other sprinter who focused on the 200m, who began to train for the 100m and in a single year knocked off over half a second from their "try-it-and-see-what-happens" time. Not knowing everything, I invite anybody to provide an example other than Bolt. For a trained 200m runner to chop more than half a second off their 100m time in a year is nuts. That is beyond absolutely huge, and IMHO is only possible for an athlete who is in an early developmental phase, maybe someone around 17/18/19 years of age.
Take a look at Bolt this year, 2012. THAT is how the real Bolt runs 100m, the same as he did in 2011 and 2010. He can still be fast, like 9.75, but that's .20 slower than his fastest. 9.75 in 2012 would be consistent with improving from 9.84/9.80 in 2008, and is entirely credible--again, not only just by the time, but HOW the time was achieved, HOW he looked sprinting that kind of time.
I do not discount the possibility that he is the outlier of all-time, I merely point out that that possibility is exceedingly unlikely.
Finally, the fact that he has never officially tested positive is not helpful to this discussion, as everyone knows by now.
Enter Blake. While I do acknowledge the possibility--however slim--that Bolt has always been clean (and also Powell), there is zero--ZERO--possibility that Blake is clean.
Absolutely zero. In my mind, this is not even a topic for discussion. I saw him coming, years ago. His WR-quality 19.26 last year was the second-biggest in-your-face performance ever witnessed in t&f, second only to Ben Johnson's 9.79 in Seoul.
Nobody needed to discuss the evidence of Johnson's juicing in Seoul--it was patently obvious, as is Blake's today. Blake is slightly less extreme than Johnson, but Johnson was actually faster then than Blake has been so far...however, I think that will change this year. Blake will show you something you though was not possible from anybody other than Bolt. It might not be at the Games, it could be later in the year--but it WILL happen, as he is fearless in his use of the juice.
And Blake's use of the juice is, IMHO, the single best evidence of Bolt's use of the juice in previous years. It all fits. Blake could only be using as he is now if Bolt had been using when Blake came on board.
Yes, I know that there is an apparent circular inadequacy in this type of reasoning--using the suggestion that Blake is using because Bolt was using, to prove that Bolt was using--however, that circularity doesn't actually exist. Bolt's having used would only provide a motive, a rationale, for Blake's using, and is not evidence of Blake's using (it only helps understand why he would use, or how he could use). So, rather than being circular, the reasoning/speculation reveals a puzzle that fits together neatly.
Again, I don't care if they're using or not. Heck, I want to see them fight it out at 9.4x, that would be absolutely epic. My only regret would be that BJ did not get the opportunity to show his full potential some 20+ years ago.
Forget BJ, what about Lewis or Bailey? Put either of those guys on a serious regimen, and they're every bit as fast as Bolt, possibly faster.
Look for Blake to follow up this year on his "in-your-face" performance of 2011. The only one who can stop him now is himself, or someone who is nuts, like a girlfriend, coach, agent, supplier, doctor, or trainer who goes off the rails, and who fails to successfully manage what amounts to extortion.