IMHO:
Check out Powell's form in Ostrava, 9.83 into a headwind, slow-mo at 2:00
http://www.youtube.com/watch?v=isZcheJIj28
See his beautifully high hip carriage, and how he seems to be dancing down the track. He got his separation in that race in the transition/top speed phase.
Right off the blocks he was nice and high, which set him up for a perfect transition and late drive phase. And by perfect, I mean perfect. Flawless.
Contrast that to the recent race in Jam where he pulled up:
http://www.youtube.com/watch?v=QwV3xUvOB_I
His hips aren't in the right position coming off the blocks. He looks like he is fighting to develop power to the track, because he is in an entirely wrong position to do so. He looks to me like a guy tangled in a big net, trying to get out--anything but smooth.
His position doesn't allow him to plant his foot at the right spot relative to his CG--he's planting it too far forward, and muscling it rearward, rather than making sure it lands in the right place where rearward force is applied to the track as soon as contact is made, as is visible in the Ostrava vid.
I don't even know if he was injured in that race--he could have bailed because he burned up so much energy trying to get out of that net that he knew it wasn't worth continuing and risking real injury as a result.
Point is that his position coming off the blocks was all wrong--as a result he was muscling it, and was not in a position to develop any speed in late drive/transition. Had he continued to run, there is absolutely no way he would have won that race, because late drive/transition is his bread and butter. In the last part of his race he can only hold onto whatever speed he has developed in that phase, and in this race, it wasn't there. He wouldn't have come even near breaking 10.
Why not? What is the problem? Injury could be one thing. More likely is lack of preparation, maybe due to inability to train well because of injury. He doesn't currently have the physical ability to start/drive like he used to, but he hasn't made any form adjustments to account for his decreased capacity.
That can be a good thing, IF he is on the road to health--why practice form that is conducive to performing with a lower ability, when you intend to achieve the higher ability necessary to make use of the good form? However, if he is not on the road to a great state of health, then he needs to learn to adjust, and to "run with his injury", which would include a slightly different start and drive mechanic.
That said, with the finishing ability he fails to show, with a different start/drive mechanic, there is no way he is going under 10.
So we have 2 possible clean scenarios:
1) he doesn't run, and tries to heal. No sub-10, since he isn't running.
2) he continues to run injured while using his healthy form. No sub-10, since he's fighting himself down the track.
If he is genuinely injured, I don't see him going sub-10 anytime soon, unless he does whatever is required to heal super-quickly, if that is even possible given the nature of his injuries.