What makes Bolt special
Having just 'smashed' his own record by 0.11 seconds (a country mile in the 100m, it took about 10 years to have that much shaved off it to get the Bolt's previous record) to set a new record of 9.58 seconds you can see why Bolt thinks 9.4 is possible.
Watching the video and looking at his split times I remember him saying that once he's up, if he's in the lead he's won. You can see how much taller he is, even in the blocks. His start is fairly 'normal' apparently, but once he's upright look how he just steams away from the others, finishing several yards clear.
He was faster than all his opponents over every sector bar reaction time off the blocks.
Bolt completed his first 30m in 3.79sec, went through 20m-40m in 1.75, 40m-60m in 1.67, 60-80 in 1.61 and 80-100 in 1.66.
He's unusual, taller athletes are supposed to have slower stride frequency, but Bolt doesn't, he's just as fast as his shorter competitors, so the extra stride length as a result of his height means he's unbeatable, until he comes up against someone with longer legs and equal frequency or faster leg speed. And he's only 22.